Battery parallel branch differential pressure self-repairing method and battery system

Abstract

The application discloses a kind of battery parallel branch pressure difference self-repairing method and battery system, belong to electric automobile technical field.In fast charging process, the total voltage of multiple parallel branches is collected in real time, when the maximum voltage difference is greater than the fault threshold, control all branch relays to be disconnected and enter self-repairing mode.In this mode, only the charging branch with the lowest total voltage is closed, and the preset equalization charging control mapping table (MAP) is switched to, and the fast charging protocol current is dynamically scaled according to the ratio of the number of closed relays to the total number of branches.The voltage difference between the charging branch and the next-lowest voltage branch not connected is dynamically monitored during charging, and the charging is limited when the voltage difference converges to the first voltage difference threshold, and the next-lowest voltage branch corresponding relay is closed and connected when the voltage difference converges to the second voltage difference threshold, and the number of relays is updated to readjust the current.The above steps are repeated until all relays are closed.The application aims to automatically eliminate the voltage difference of the charging branch and avoid voltage difference fault shutdown.

Description

Technical Field

[0001] This invention relates to the field of power battery topology control and charging management technology, and in particular to a method for self-repairing voltage difference in parallel branches of a battery and a battery system. Background Technology

[0002] In new energy heavy-duty trucks and mining transport vehicles, standard battery boxes are typically used in series and parallel connections to construct high-voltage and large-capacity power battery systems, thereby meeting the demands of high-power charging and discharging. However, due to inconsistencies in the manufacturing and usage of individual battery cells, coupled with the rapid heat generation caused by high-frequency, high-current uphill discharge and downhill braking energy feedback under complex mining conditions, and the uneven heat dissipation issues often encountered by liquid cooling systems in multi-branch topologies, significant total voltage differences easily arise between parallel branches, leading to frequent branch voltage difference faults and forced vehicle shutdowns. Currently, the common repair method for addressing the problem of excessive voltage differences between parallel branches mainly relies on passive balancing performed by the battery management system within the battery box. However, passive balancing often requires the vehicle to remain stationary for several hours with extremely low balancing current, which cannot meet the continuous high-intensity operation requirements of new energy mining trucks without any downtime. Another conventional approach is to remove the entire battery pack cover during the after-sales maintenance phase and use a specialized equalization instrument to charge and discharge each cell individually for repair. This maintenance method is not only extremely labor-intensive but also incurs very high labor costs, which seriously reduces the vehicle's operating efficiency.

[0003] For example, CN110854965A discloses a multi-channel parallel lithium battery system and its control method, which achieves voltage consistency among multiple channels through the cooperation of BMS, multiple branch modules, branch relays, equalization module, charging module and discharging module; however, this solution still does not provide a complete design for prioritizing the lowest branch to charge after a branch voltage difference fault during DC fast charging of the vehicle, switching the equalization charging control mapping table, dynamically scaling the fast charging protocol current according to the number of closed relays and threshold current limiting and incorporation control.

[0004] Therefore, how to automatically and efficiently achieve self-repair of the differential pressure of parallel branches during the charging process to avoid downtime has become an urgent technical problem to be solved. Summary of the Invention

[0005] The main objective of this invention is to provide a battery parallel branch voltage differential self-repair method and battery system, which aims to automatically and efficiently achieve parallel branch voltage differential self-repair during charging to avoid downtime.

[0006] To achieve the above objectives, this invention proposes a battery parallel branch voltage difference self-repair method, executed by a battery management system, comprising: During the DC fast charging process of the vehicle, the total voltage of M parallel branches is collected, M≥2 and is an integer, and each parallel branch is equipped with an independently controlled branch relay. When the voltage difference between the highest total voltage and the lowest total voltage exceeds the preset fault threshold, all branch relays are disconnected and the differential voltage self-repair mode is entered. The differential pressure self-healing mode includes: Only the parallel branch with the lowest current total voltage is closed as the target charging branch, and the system switches to the equalization charging control mapping table with the current state of charge, current battery temperature, number of closed relays N and total number of branches M as inputs and equalization charging reference current and target limit current as outputs. The fast charging protocol current requested from external charging piles is dynamically scaled according to N / M, and the amplitude of the fast charging protocol current changes in a positive correlation with N. During the charging process, the real-time voltage difference between the target charging branch and the branch with the lowest total voltage among the unconnected parallel branches is monitored. When the real-time voltage difference is less than the first voltage difference threshold, the current is limited to the target limiting current. When the real-time voltage difference is less than the second voltage difference threshold, the branch relay of the lowest branch is closed and N is updated. Repeat the scaling, monitoring, current limiting, and merging steps described above until all the branch relays corresponding to the M parallel branches are closed.

[0007] Preferably, the process is triggered by the following interactive steps before entering the differential pressure self-healing mode: The battery management system sends a balancing charging request to the vehicle controller, which then controls the vehicle's dashboard to display a fault message indicating excessive branch voltage difference. When the battery management system receives a driver confirmation command from the vehicle's instrument panel, it controls the branch relay corresponding to the parallel branch with the lowest current total voltage to close, thereby switching to the differential pressure self-repair mode.

[0008] Preferably, the preset fault threshold is 25V, the first differential voltage threshold is 10V, the second differential voltage threshold is 3V, and the target limiting current is 15A.

[0009] Preferably, the steps are repeated in a rolling manner until... After all the branch relays corresponding to the parallel branches are closed, the method further includes the following exit step: Continue to dynamically monitor the real-time voltage difference between the highest and lowest total voltages in the battery system. When the real-time voltage difference between the highest and lowest total voltages is less than the third voltage difference threshold, control to exit the voltage difference self-repair mode and restore the fast charging protocol current command generated according to the fast charging MAP in the normal fast charging mode. The third differential pressure threshold is 8V.

[0010] Preferably, in the dynamic scaling adjustment, the fast charging protocol current requested from the external charging station is quantitatively calculated using the following formula:

[0011] in, The fast charging protocol current actually requested from external charging stations. The set equalization charging reference current command.

[0012] Preferably, the battery system includes four parallel branches, and the total number of branches is... The high-voltage circuits of the four parallel branches are respectively equipped with a first branch relay, a second branch relay, a third branch relay, and a fourth branch relay, and the first branch relay, the second branch relay, the third branch relay, and the fourth branch relay are all independently driven and limited by the battery management system.

[0013] Preferably, during the operation of the differential pressure self-healing mode, a parallel circuit safety disconnection monitoring step is also included: The battery management system collects the dynamic branch current of each branch in real time by using branch current sensors installed on each of the parallel branches. If the dynamic branch current of any parallel branch in which the closed branch relay is located exceeds the preset circulating current limit, the battery management system controls the disconnection of the branch relay corresponding to the parallel branch and issues an external charging pile to stop charging.

[0014] Preferably, during the operation of the differential pressure self-healing mode, the following battery temperature closed-loop monitoring step is also included: The battery management system collects the current battery temperature of each of the parallel branches in real time and calculates the corresponding battery temperature change rate. ; If the battery temperature change rate of any of the connected parallel branches If the temperature change rate exceeds the preset safe range, the battery management system determines that the current self-repair charging heat generation is abnormal, and controls the disconnection of all currently closed branch relays to forcibly limit the current and terminate the differential pressure self-repair mode.

[0015] Preferably, the dynamic monitoring and rolling repetition step further includes an accompanying transient risk assessment step: Real-time data collection Total branch voltage at each time point and the Total branch voltage at each time point Calculate the real-time voltage change value and transient voltage change rate ,in, For the first Total branch voltage at each time point For the first Total branch voltage at each time point This represents the real-time voltage change value. The transient voltage change rate, For the first From the time point to the The time difference at each point in time. The time point number; The battery management system will calculate the transient voltage change rate. The risk level is compared in real time with five preset risk levels from low to high. The first risk level range is... The second risk level range is The third risk level range is The fourth risk level range is The fifth risk level range is , , , , As a preset voltage change rate threshold, when the transient voltage change rate When the risk level falls into the highest fifth risk level range, the battery management system outputs a severe overvoltage thermal mutation warning signal and controls the disconnection of the high-voltage circuit of the entire vehicle.

[0016] Preferably, after the differential pressure self-healing mode is completed and all the branch relays are closed and deactivated, the battery management system further performs the following adaptive correction step for the next self-healing control: Record the actual voltage change rate for each parallel branch after the repair is completed, and calculate the arithmetic mean of the voltage change rates for all parallel branches. ; Calculate the absolute value of the ratio of the deviation between the actual voltage change rate and the arithmetic mean of each of the parallel branches. ; The absolute value of the deviation ratio From the formula The calculation shows that, This is the arithmetic mean of the rates of change of voltage in all parallel branches. For the first The actual voltage change rate of each parallel branch The parallel branch number is used to determine if the absolute value corresponding to any of the parallel branches is greater than a preset deviation threshold. If so, an electrical component fault diagnosis prompt signal will be generated and reported. If the absolute value corresponding to all the parallel branches is not greater than the preset deviation threshold Based on the current voltage change rate difference of each of the parallel branches, when the differential voltage self-repair mode is activated again, the original preset switching time (the equalization charging time used to control the individual closing of the branch relays) will be used. Based on the formula Determine the equalization charging switching time of the corresponding branch relay next time. ,in, To correct the direction coefficient, when the first When the actual voltage change rate of the parallel branch is lower than the arithmetic mean, a positive value is taken to extend the equalization charging switching time. When the actual voltage change rate of each parallel branch is higher than the arithmetic mean, a negative value is taken to shorten the equalization charging switching time. This is the preset time correction factor.

[0017] This application also discloses a battery system, including: There are M parallel branches, each with an independently controlled branch relay on its high-voltage circuit, where M ≥ 2 and is an integer; and The battery management system is electrically connected to each of the branch relays. The battery management system includes a voltage acquisition unit, a relay control unit, a mapping table calling unit, and a charging current request unit. The voltage acquisition unit is used to acquire the total voltage of each parallel branch. The relay control unit is used to independently open and close each branch relay. The mapping table calling unit is used to switch to the equalization charging control mapping table. The charging current request unit is used to adjust the fast charging protocol current requested from the external charging pile according to the ratio of the number of closed branch relays to the total number of branches.

[0018] The above technical solution has the following advantages: By dynamically monitoring the total voltage of each parallel branch during DC fast charging of the vehicle, and actively disconnecting all branch relays to enter differential voltage self-repair mode when the differential voltage exceeds the limit, the high-voltage circuit can be effectively isolated and the risk of inrush circulating current when multiple branches are connected in parallel can be completely eliminated. In self-repair mode, the parallel branch with the lowest total voltage is precisely located and prioritized for individual charging. At the same time, the fast charging MAP is switched to the equalization charging MAP, and the requested current is dynamically scaled and adjusted according to the ratio of the number of currently closed relays to the total number of branches. This achieves stable derating of high-voltage electrical power in single-branch or low-branch charging states, ensuring that parallel branches in the charging state will not experience current overload. During the charging voltage boosting process, the voltage difference between the target charging branch and the unconnected second-lowest voltage branch is monitored in real time. When the voltage difference converges to the first voltage difference threshold, the current is forcibly limited to the target limiting current. This allows the charging branch voltage to approach the next branch to be connected at a slow and safe speed, thereby ensuring a smooth transition of the circuit voltage when the subsequent second-lowest voltage branch is connected, avoiding problems such as arcing or local strong inrush current caused by transient voltage difference. By repeatedly executing the current limiting convergence and branch safe integration operations, the system ultimately achieves automatic elimination of pressure difference and stable grid connection for all parallel branches. The entire process is executed automatically in a closed loop during charging, eliminating the need for long-term vehicle idling or manual unpacking and maintenance. This significantly improves the continuous operating efficiency of new energy vehicles and reduces after-sales maintenance costs. Attached Figure Description

[0019] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings, wherein: Figure 1 A flowchart of a battery parallel branch voltage differential self-repair method provided in an embodiment of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1 combined Figure 1This embodiment provides a self-repair method for voltage difference in parallel battery branches, which is executed by the battery management system. This battery system is mainly used in large pure electric vehicles such as new energy mining trucks, using a series-parallel combination of standard battery boxes to meet the high current and high capacity requirements during vehicle operation. Due to differences in cell consistency and uneven liquid cooling caused by complex mining conditions, significant total voltage differences can easily occur between parallel branches within the battery system. This method aims to automatically reduce branch voltage differences during DC fast charging, preventing vehicle shutdown due to voltage difference faults. The battery system includes... One parallel branch, of which It is an integer greater than or equal to 2. In this embodiment, a high-voltage topology containing four parallel branches is used as an example for detailed explanation, i.e., the total number of branches. These four parallel branches are designated as the first parallel branch, the second parallel branch, the third parallel branch, and the fourth parallel branch. Corresponding high-voltage relays for each branch are installed on their respective high-voltage circuits, and all branch relays are independently controlled by the battery management system (BMS). Furthermore, each parallel branch is equipped with a branch current sensor to monitor the current state within the branch in real time. The entire battery system establishes an electrical connection and communication network with external charging piles, the vehicle, and the vehicle's dashboard via high-voltage wiring harnesses and copper busbars. When the number of parallel branches is any integer greater than or equal to two, the BMS executes the same current scaling, real-time differential voltage monitoring, current limiting convergence, and branch integration steps in a rolling manner. The four-branch structure in this embodiment is merely an example.

[0022] During DC fast charging of a vehicle, this method first performs a real-time voltage acquisition step. When a pure electric vehicle is connected to an external charging station via a charging gun, the charging connector of the high-voltage circuit is connected to the external power supply harness, and the battery management system is then activated and enters the working state. The battery management system connects the standard battery boxes in each parallel branch in series via a low-voltage communication line and utilizes a specific bus protocol, thereby enabling control of the battery system. Real-time acquisition of the total voltage of each parallel branch in a series of parallel branches. Within a specific sampling period, the battery management system reads the voltage performance of each branch at the current moment, for example, acquiring the voltage of the first branch. Total branch voltage at each time point and the Total branch voltage at each time point This allows us to obtain dynamic voltage change data for each parallel branch during the charging process.

[0023] After obtaining the total voltage of each parallel branch, the battery management system calculates and compares the maximum voltage difference among all parallel branches in real time. The battery management system locates and records the branch with the highest total voltage and the branch with the lowest total voltage. When the real-time voltage difference between the highest and lowest total voltages among all parallel branches exceeds a preset fault threshold, the battery management system determines that the system has triggered a branch voltage difference too large alarm. In this embodiment, the preset fault threshold is set as follows: Once the voltage difference between the highest and lowest total voltage exceeds... To prevent excessive charging from causing a large inrush current in the high-voltage branches, the battery management system immediately disconnects all branch relays, cutting off the high-voltage circuit and controlling the system to enter differential pressure self-repair mode. Before officially entering differential pressure self-repair mode, this method can also be safely triggered via an interactive step. The battery management system first sends a balancing charging request message to the vehicle controller, which then controls the vehicle's dashboard to display a fault message indicating excessive differential pressure in the branch. When the driver confirms the connection on the vehicle's dashboard, the battery management system receives the confirmation command from the dashboard. Only then does the corresponding control command take effect and officially close the corresponding relays to enter differential pressure self-repair mode, effectively avoiding the risk of high-voltage misoperation.

[0024] After the differential pressure self-repair mode is officially operational, the system performs target charging branch location and initial access control. In the currently disconnected high-voltage topology, the battery management system accurately locates the parallel branch with the lowest total voltage and designates it as the target charging branch for the current cycle. At this time, it controls and closes only the independent branch relay corresponding to this target charging branch. For example, if the total voltage of the fourth parallel branch is the lowest among all branches, the battery management system locks the fourth parallel branch as the target charging branch and issues a drive command to close the fourth branch relay, while the remaining first, second, and third branch relays remain open. Since only the single branch with the lowest total voltage is conducting at this time, the charging current provided by the external charging pile will be safely injected into this target charging branch for replenishment and boosting. Other branches in the high-voltage circuit are safely isolated because their corresponding relays are open, thus completely eliminating the circulating current hazard when multiple branches are connected in parallel.

[0025] Upon successful connection to the target charging branch, the battery management system immediately switches the conventional fast charging control map (MAP) to a preset equalization charging control map (MAP). Since only some branches, or even just a single branch, are active in the high-voltage battery system, continuing to use the fast charging protocol current commands generated by the fast charging MAP under the conventional fast charging mode would severely exceed the current load on a single branch. Therefore, under the equalization charging MAP, the equalization charging MAP includes at least the number of branch relays with the current state of charge, current battery temperature, and closed state. and total number of branches As input, to balance the charging reference current The mapping relationship between the target limiting current and the output; the battery management system will first obtain the number of branch relays that are currently in a closed state. Next, based on the number of branch relays currently in a closed state... Total number of branches in the battery system The battery management system dynamically scales and adjusts the fast charging protocol current requested from external charging stations to match the ratio of the requested current to the number of currently closed relays. They exhibit a positive correlation. Specifically, the actual fast charging protocol current requested from external charging stations is determined by the formula:

[0026] In the above formula, The fast charging protocol current actually requested from external charging stations. This is the set equalization charging reference current command. Calculated using this formula, when only a single target charging branch is closed, the number... The total number of branches is 1. With a current rating of 4, the actual current requested from the external charging station is safely limited to one-quarter of the reference current command, thereby achieving a smooth derating of the charging power and ensuring high-voltage electrical safety during the charging process of a single branch.

[0027] Table 1 shows an example mapping relationship for the equalization charging MAP:

[0028] During the limited charging process of the target charging branch, its internal standard battery box continuously absorbs energy, causing the total voltage of the branch to rise continuously. During this period, the battery management system (BMS) performs a dynamic differential voltage monitoring step, monitoring and calculating the real-time voltage difference between the current total voltage of the target charging branch and the second-lowest voltage branch among all parallel branches not currently connected to the high-voltage circuit. As the voltage of the target charging branch continues to rise, the real-time voltage difference between it and the second-lowest voltage branch gradually converges and decreases. When the BMS detects that the real-time voltage difference has converged to less than a first voltage difference threshold, to ensure a smooth transition of the circuit voltage when a new branch is connected, and to prevent arcing or localized inrush current due to transient voltage differences, the BMS controls the fast charging protocol current requested from the external charging pile to be forcibly limited to the target limiting current, thus performing refined current-limited charging convergence on the connected target charging branch. In this embodiment, the first voltage difference threshold is specifically preset as follows: The target limiting current is specifically preset as follows: This means that when the voltage difference between the total voltage of the charging branch and the voltage of the second lowest voltage branch decreases to... When the current is below a certain threshold, the battery management system will forcibly limit the current requested from the external charging station to a certain level. The tiny level of voltage allows the voltage of the target charging branch to approach that of the second-lowest voltage branch at an extremely slow and controllable rate.

[0029] The current-limited charging convergence process continues until the real-time voltage difference between the current total voltage of the target charging branch and the second lowest voltage branch further converges to less than the second voltage difference threshold. This indicates that the voltages between the two branches are now very close, reaching a completely safe grid connection window. In this embodiment, the second voltage difference threshold is specifically preset to... When the real-time pressure difference between the two is less than At this time, the battery management system outputs a control signal to close the independent branch relay corresponding to the low-voltage branch, thus successfully connecting the low-voltage branch into the already connected parallel high-voltage circuit. With the successful connection of the low-voltage branch, the total number of parallel branches in the high-voltage circuit increases, and the battery management system updates the number of branch relays in the closed state accordingly. The value, for example, the quantity The battery management system was updated from 1 to 2. Because an additional branch was added to share the current, the charging current limit that the entire high-voltage system could withstand increased exponentially. At this point, the battery management system updated the current limit again. Substituting the values ​​into the formula, the fast charging protocol current requested from the external charging station is recalculated and adjusted to half of the equalization charging reference current command. After this integration is completed, the method enters the rolling repetition phase, that is, the above-mentioned current scaling adjustment, real-time differential voltage monitoring, current limiting convergence, and branch integration steps are repeatedly executed. In the next cycle, the method continues to search for the second lowest voltage branch among the remaining unconnected branches and integrates it when its differential voltage converges to... Time limit to When the pressure difference converges to The corresponding third branch relay is closed, and so on, until the entire battery system is closed. All the branch relays corresponding to the parallel branches were successfully closed.

[0030] Repeat the above steps until... After all the branch relays corresponding to the parallel branches are closed, this method enters the final exit and normal fast charging recovery phase. At this time, although all branch relays are closed, the battery management system continues to dynamically monitor the real-time voltage difference between the highest and lowest total voltage in the battery system to ensure that the voltage difference across the entire system has been completely eliminated. When the battery management system detects that the real-time voltage difference between the highest and lowest total voltage is less than the third voltage difference threshold, the control system officially exits the voltage difference self-repair mode and restores the vehicle's normal fast charging mode based on the fast charging protocol current command generated according to the fast charging MAP. In this embodiment, the third voltage difference threshold is specifically preset as follows: When the real-time voltage difference between the highest and lowest branches in the system is less than When the voltage difference between each branch has been successfully self-repaired, the battery management system exits the equalization charging process, switches the equalization charging MAP back to the normal fast charging MAP, and generates a fast charging protocol current request according to the fast charging MAP for high-efficiency fast charging. After fast charging is completed and the battery is fully charged, the high-voltage charging gun is disconnected, the vehicle controller exits the corresponding charging request, and the voltage difference fault status is restored and cleared on the bus, thus fully realizing the fully automatic closed-loop self-repair of voltage difference faults in the multi-branch battery system during the charging process.

[0031] Example 2 As a further extension of the above core embodiment, this embodiment provides a battery parallel branch differential pressure self-repair method accompanied by a parallel circuit safety disconnection monitoring step. During operation in differential pressure self-repair mode, the battery management system collects the dynamic branch current of each parallel branch in real time through branch current sensors respectively installed on the first, second, third, and fourth parallel branches. Since only some branch relays are closed in the initial stage of self-repair charging, internal circulating currents may occur between the conducting and non-conducting branches, and when multiple branches are subsequently connected to the grid, due to the dynamic changes in the high-voltage circuit topology, caused by transient electromotive force differences. To prevent large current circulating currents from damaging the battery box or high-voltage fuses, the battery management system compares the real-time collected dynamic branch currents with a preset circulating current limit, which is specifically set, for example, as follows: If the dynamic branch current of any parallel branch containing a closed branch relay exceeds the preset circulating current limit, the battery management system determines that there is a serious electrical performance abnormality or short-circuit overcurrent risk in the current circuit. It then controls the rapid disconnection of the branch relay corresponding to the parallel branch, cuts off the high-voltage path of the branch, and simultaneously sends a stop charging command to the external charging pile through the communication bus, forcibly terminating the entire DC fast charging process, thereby providing multi-level electrical safety protection.

[0032] Example 3 As another core safety monitoring improvement of the differential pressure self-repair method of this invention, this embodiment introduces a comprehensive closed-loop monitoring step for battery temperature during operation in differential pressure self-repair mode. When a pure electric mining truck is fast-charging at high power or performing self-repair charging, the individual cells in the standard battery box will rapidly generate heat due to the high-current charging. If the vehicle's liquid cooling plate has uneven heat dissipation or the internal resistance of some cells is too high, localized heat accumulation can easily occur. Therefore, the battery management system uses temperature acquisition components built into each standard battery box to collect the current battery temperature of each parallel branch in real time and calculates the corresponding battery temperature change rate based on the set sampling period. The battery management system has a preset safe temperature change rate range, which is specifically set to, for example, no greater than... During self-healing operation, if the battery temperature change rate of any parallel branch already connected to the high-voltage circuit... The temperature change rate has exceeded the preset safe range, meaning the current rate of temperature increase is greater than... If the battery management system determines that the current self-repair charging is generating abnormal heat, there is a potential safety hazard of thermal runaway in the battery system. At this time, the battery management system will immediately issue a high-voltage cut-off command to disconnect all currently closed branch relays, completely cutting off the high-voltage charging circuit of the entire vehicle, thereby forcibly limiting the current and terminating the differential pressure self-repair mode, ensuring the absolute safety of the vehicle under extreme heat generation conditions.

[0033] Example 4 As a transient risk warning mechanism for the differential pressure self-healing method of this invention, this embodiment also includes a transient risk assessment step during dynamic monitoring and rolling repetition. The battery management system collects data in real time at a high-frequency sampling rate. Total branch voltage at each time point and the Total branch voltage at each time point It automatically calculates the real-time voltage change value based on the difference formula. Subsequently, the battery management system further incorporates time difference... Quantitatively calculate the rate of change of transient voltage ,in, For the first Total branch voltage at each time point For the first Total branch voltage at each time point This represents the real-time voltage change value. The transient voltage change rate, For the first From the time point to the The time span between points in time This refers to the time point sequence number. To achieve multi-level, refined risk control, the battery management system will calculate the transient voltage change rate. The risk level is compared in real time with five preset risk levels from low to high. The first risk level range is... The second risk level range is The third risk level range is The fourth risk level range is The fifth risk level range is , , , , The preset voltage change rate threshold is satisfied. When the battery management system detects a transient voltage change rate in a parallel branch... When a voltage spike occurs and falls into the highest risk level (Level 5), it indicates an extremely drastic voltage change in that branch, typically caused by a severe overvoltage fault, a broken sampling harness, or a sudden thermal change within the battery cell. Once this highest risk level is triggered, the battery management system will immediately output a severe overvoltage / thermal change warning signal and, within milliseconds, control the disconnection of the entire vehicle's high-voltage circuit to prevent damage to the power battery system from overcharging.

[0034] Example 5 As an adaptive optimization scheme to improve long-term balancing performance, this embodiment, after the differential pressure self-repair mode is completed and all branch relays are closed and deactivated, controls the battery management system to perform an adaptive correction step for the balancing strategy for the next self-repair control. Because there are objective differences in the aging degree, health status, and actual internal resistance of the batteries in each parallel branch, a fixed control time may not consistently achieve the optimal self-repair effect in subsequent use. Therefore, in this embodiment, the battery management system completely records the actual voltage change rate of each parallel branch from the start to the end of this repair, and calculates the arithmetic mean of the voltage change rates of all parallel branches. Next, the battery management system sequentially calculates the actual voltage change rate of each parallel branch and its arithmetic mean. The absolute value of the deviation ratio between That is, through the formula The absolute value is calculated, where, This is the arithmetic mean of the rates of change of voltage in all parallel branches. For the first The actual voltage change rate of each parallel branch This refers to the parallel branch number. If the absolute value corresponding to any parallel branch is greater than a preset deviation threshold... The preset deviation threshold For example, set as If the absolute value is less than or equal to the preset deviation threshold, it indicates a significant deviation in the charging / discharging performance or sensor sampling component of that specific branch compared to the other parallel branches, suggesting potential device damage. In this case, the battery management system triggers and generates an electrical component fault diagnosis signal and reports it, facilitating accurate maintenance by after-sales personnel. Conversely, if the absolute value for all parallel branches is not greater than the preset deviation threshold, the system will detect the fault. This indicates that the hardware status of each branch is within the normal aging range. At this time, the battery management system adaptively adjusts the balancing strategy for the next activation of the differential voltage self-repair mode based on the actual voltage change rate difference of each parallel branch. Specifically, the adjustment is made within the original preset switching time (the balancing charging time used to control the individual closing of the branch relays). Based on the formula Determine the equalization charging switching time of the corresponding branch relay next time. ,in, To correct the direction coefficient, when the first The actual voltage change rate of each parallel branch is lower than the arithmetic mean. When a positive value is taken, the equalization charging time of the corresponding branch relay when it is closed individually is extended. The actual voltage change rate of each parallel branch is higher than the arithmetic mean. The time is negative to shorten the corresponding equalization charging switching time. By setting a preset time correction coefficient, a closed-loop self-evolution of the control strategy is achieved.

[0035] Example 6 This embodiment provides a battery system capable of fully implementing the battery parallel branch voltage differential self-repair method described in any of the above embodiments. This battery system is mainly integrated into the high-voltage power architecture of a pure electric mining truck, specifically including M parallel branches and a battery management system electrically connected to the relays of each branch. In this embodiment, the total number of branches M=4, namely, a first parallel branch, a second parallel branch, a third parallel branch, and a fourth parallel branch. Each parallel branch has an independently controlled branch relay on its high-voltage circuit, specifically a first branch relay, a second branch relay, a third branch relay, and a fourth branch relay. Each parallel branch internally consists of multiple standard battery boxes connected in series, for example, four power battery boxes connected in series to form an independent branch, in order to output sufficient high-voltage power. The battery system also includes a high-voltage box, which serves as the core module for controlling the high-voltage switching, and internally integrates the main core of the battery management system, the relays of each branch, and corresponding high-voltage sockets and other electrical components. Each branch establishes a complete current path through the high-voltage power transmission harness, battery positive plug, battery negative plug, charging positive plug, and charging negative plug. Branch current sensors are connected in series in the high-voltage circuit of each branch to report the collected branch current to the battery management system in real time. The battery management system integrates a central control chip, storage module, analysis and calculation module, and voltage and temperature acquisition components. It receives cell data uploaded by each power battery box via a specific bus protocol through a low-voltage communication line. When the total voltage difference of the branch is detected to meet the self-repair trigger condition, the battery management system independently controls the switching of each branch relay through the drive circuit, performing voltage acquisition, voltage difference judgment, lowest branch connection, equalization charging control mapping table switching, current scaling, current limiting integration, and exit control.

[0036] It should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for self-repairing voltage difference in parallel battery branches, executed by a battery management system, comprising: During the DC fast charging process of the vehicle, the total voltage of M parallel branches is collected, M≥2 and is an integer, and each parallel branch is equipped with an independently controlled branch relay. When the voltage difference between the highest total voltage and the lowest total voltage exceeds the preset fault threshold, all branch relays are disconnected and the differential voltage self-repair mode is entered. The differential pressure self-healing mode is characterized by including: Only the parallel branch with the lowest current total voltage is closed as the target charging branch, and the system switches to the equalization charging control mapping table with the current state of charge, current battery temperature, number of closed relays N and total number of branches M as inputs and equalization charging reference current and target limit current as outputs. The fast charging protocol current requested from external charging piles is dynamically scaled according to N / M, and the amplitude of the fast charging protocol current changes in a positive correlation with N. During the charging process, the real-time voltage difference between the target charging branch and the branch with the lowest total voltage among the unconnected parallel branches is monitored. When the real-time voltage difference is less than the first voltage difference threshold, the current is limited to the target limiting current. When the real-time voltage difference is less than the second voltage difference threshold, the branch relay of the lowest branch is closed and N is updated. Repeat the scaling, monitoring, current limiting, and merging steps described above until all the branch relays corresponding to the M parallel branches are closed.

2. The battery parallel branch voltage difference self-repair method according to claim 1, characterized in that, Before entering the differential pressure self-healing mode, it is triggered by the following interactive steps: The battery management system sends a balancing charging request to the vehicle controller, which then controls the vehicle's dashboard to display a fault message indicating excessive branch voltage difference. When the battery management system receives a driver confirmation command from the vehicle's instrument panel, it controls the branch relay corresponding to the parallel branch with the lowest current total voltage to close, thereby switching to the differential pressure self-repair mode.

3. The battery parallel branch voltage difference self-repair method according to claim 1, characterized in that, The preset fault threshold is 25V, the first differential voltage threshold is 10V, the second differential voltage threshold is 3V, and the target limiting current is 15A.

4. The battery parallel branch voltage difference self-repair method according to claim 1 or 3, characterized in that, Repeat the steps in a rolling manner until... After all the branch relays corresponding to the parallel branches are closed, the method further includes the following exit step: Continue to dynamically monitor the real-time voltage difference between the highest and lowest total voltages in the battery system. When the real-time voltage difference between the highest and lowest total voltages is less than the third voltage difference threshold, control to exit the voltage difference self-repair mode and restore the fast charging protocol current command generated according to the fast charging MAP in the normal fast charging mode. The third differential pressure threshold is 8V.

5. The battery parallel branch voltage difference self-repair method according to claim 1, characterized in that, In the aforementioned dynamic scaling adjustment, the fast charging protocol current requested from the external charging station is quantitatively calculated using the following formula: in, The fast charging protocol current actually requested from external charging stations. The set equalization charging reference current command.

6. The battery parallel branch voltage difference self-repair method according to claim 1, characterized in that, The battery system includes four parallel branches, and the total number of branches is... The high-voltage circuits of the four parallel branches are respectively equipped with a first branch relay, a second branch relay, a third branch relay, and a fourth branch relay, and the first branch relay, the second branch relay, the third branch relay, and the fourth branch relay are all independently driven and limited by the battery management system.

7. The battery parallel branch voltage difference self-repair method according to claim 1, characterized in that, During operation of the differential pressure self-healing mode, a parallel loop safety disconnection monitoring step is also included: The battery management system collects the dynamic branch current of each branch in real time by using branch current sensors installed on each of the parallel branches. If the dynamic branch current of any parallel branch in which the closed branch relay is located exceeds the preset circulating current limit, the battery management system controls the disconnection of the branch relay corresponding to the parallel branch and issues an external charging pile to stop charging.

8. The battery parallel branch voltage difference self-repair method according to claim 1, characterized in that, During the operation of the differential pressure self-healing mode, the following battery temperature closed-loop monitoring steps are also included: The battery management system collects the current battery temperature of each of the parallel branches in real time and calculates the corresponding battery temperature change rate. ; If the battery temperature change rate of any of the connected parallel branches If the temperature change rate exceeds the preset safe range, the battery management system determines that the current self-repair charging heat generation is abnormal, and controls the disconnection of all currently closed branch relays to forcibly limit the current and terminate the differential pressure self-repair mode.

9. The battery parallel branch voltage difference self-repair method according to claim 1, characterized in that, The dynamic monitoring and rolling repetition steps also include an accompanying transient risk assessment step: Real-time data collection Total branch voltage at each time point and the Total branch voltage at each time point Calculate the real-time voltage change value and transient voltage change rate ,in, For the first Total branch voltage at each time point For the first Total branch voltage at each time point This represents the real-time voltage change value. The transient voltage change rate, For the first From the time point to the The time difference at each point in time. The time point number; The battery management system will calculate the transient voltage change rate. The risk level is compared in real time with five preset risk levels from low to high. The first risk level range is... The second risk level range is The third risk level range is The fourth risk level range is The fifth risk level range is , , , , As a preset voltage change rate threshold, when the transient voltage change rate When the risk level falls into the highest fifth risk level range, the battery management system outputs a severe overvoltage thermal mutation warning signal and controls the disconnection of the high-voltage circuit of the entire vehicle.

10. The battery parallel branch voltage difference self-repair method according to claim 1, characterized in that, After the differential pressure self-healing mode is completed and all the branch relays are closed and deactivated, the battery management system also performs the following adaptive correction steps for the next self-healing control: Record the actual voltage change rate for each parallel branch after the repair is completed, and calculate the arithmetic mean of the voltage change rates for all parallel branches. ; Calculate the absolute value of the ratio of the deviation between the actual voltage change rate and the arithmetic mean of each of the parallel branches. ; The absolute value of the deviation ratio From the formula The calculation shows that, This is the arithmetic mean of the rates of change of voltage in all parallel branches. For the first The actual voltage change rate of each parallel branch The parallel branch number is used to determine if the absolute value corresponding to any of the parallel branches is greater than a preset deviation threshold. If so, an electrical component fault diagnosis prompt signal will be generated and reported. If the absolute value corresponding to all the parallel branches is not greater than the preset deviation threshold Based on the current voltage change rate difference of each of the parallel branches, when the differential voltage self-repair mode is activated again, the original preset switching time (the equalization charging time used to control the individual closing of the branch relays) will be used. Based on the formula Determine the equalization charging switching time of the corresponding branch relay next time. ,in, To correct the direction coefficient, when the first When the actual voltage change rate of the parallel branch is lower than the arithmetic mean, a positive value is taken to extend the equalization charging switching time. When the actual voltage change rate of each parallel branch is higher than the arithmetic mean, a negative value is taken to shorten the equalization charging switching time. This is the preset time correction factor.

11. A battery system, characterized in that, include: There are M parallel branches, each with an independently controlled branch relay on its high-voltage circuit, where M ≥ 2 and is an integer; and The battery management system is electrically connected to each of the branch relays. The battery management system includes a voltage acquisition unit, a relay control unit, a mapping table calling unit, and a charging current request unit. The voltage acquisition unit is used to acquire the total voltage of each parallel branch. The relay control unit is used to independently open and close each branch relay. The mapping table calling unit is used to switch to the equalization charging control mapping table. The charging current request unit is used to adjust the fast charging protocol current requested from the external charging pile according to the ratio of the number of closed branch relays to the total number of branches.

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