Discharge control method and system for power battery system, and electronic device and storage medium

Abstract

A discharge control method and system for a power battery system, and an electronic device and a storage medium. The method comprises: upon detecting an upper high-voltage request instruction, acquiring a voltage value of a first battery pack (110) and a voltage value of a second battery pack (120) (S301); determining whether the difference between the voltage value of the first battery pack (110) and the voltage value of the second battery pack (120) is less than a first voltage threshold value (S302); when the difference is less than the first voltage threshold value, controlling a power battery system to enter a parallel discharge mode (S303); when the difference is greater than or equal to the first voltage threshold value, controlling the power battery system to enter a partial discharge mode (S304); and during the process of the partial discharge mode, if the difference is less than a second voltage threshold value, controlling the power battery system to switch to the parallel discharge mode (S305). The method is used for solving the problem of the consistency between different battery packs being relatively poor.

Description

Power battery system discharge control method, system, electronic device and storage medium

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on August 17, 2023, with application number 202311042821.7. The entire contents of the above application are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of battery charging and discharging, for example, to a power battery system discharge control method, system, electronic device and storage medium. Background Art

[0003] As the number of new energy electric vehicles increases, the disadvantage of long charging times (fast charging takes approximately one hour) is becoming increasingly prominent, becoming a key challenge that must be addressed to promote the widespread adoption of electric vehicles. To achieve higher charging rates, major battery manufacturers and charging station manufacturers have introduced high-voltage system architectures to meet fast charging needs. Taking electric vehicle charging stations as an example, charging station manufacturers offer high-voltage system architectures ranging from approximately 550V to 930V. However, most electric vehicles on the market use low-voltage system architectures (approximately 230V to 450V). To balance the high and low voltage system architecture requirements between charging stations and electric vehicles, battery manufacturers need to optimize the design of power battery systems and charge and discharge control strategies.

[0004] In the related art, the power battery is configured with two low-voltage battery packs. After the two low-voltage battery packs are connected in series for fast charging, a low-voltage battery pack is used to supply power to the load through a specific conversion module, or two low-voltage battery packs are connected in parallel to supply power to the load. However, both methods may lead to poor voltage consistency between the two low-voltage battery packs. If two battery packs are used to discharge the load at the same time, the performance differences (such as internal resistance) between the battery packs themselves, as well as the differences in aging degree, working environment, etc. during the long-term charging and discharging process, will lead to poor consistency between different battery packs; if a single battery pack is used to discharge the load alone, the consistency of different battery packs will also be poor due to the inconsistent discharge conditions of the battery packs.

[0005] Summary of the Invention

[0006] The present application provides a power battery system discharge control method to solve the problem of poor consistency among different battery packs in the power battery discharge control method in the related art.

[0007] In a first aspect, the present application provides a power battery system discharge control method, which is applied to a control module in a power battery system;

[0008] The method comprises:

[0009] When an upper high voltage request instruction is detected, obtaining voltage values ​​of a first battery pack and a second battery pack in the power battery system;

[0010] determining whether a difference between the voltage values ​​of the first battery pack and the second battery pack is less than a first voltage threshold;

[0011] In response to the difference being less than a first voltage threshold, controlling the power battery system to enter a parallel discharge mode;

[0012] In response to the difference being greater than or equal to a first voltage threshold, controlling the power battery system to enter a partial discharge mode;

[0013] During the partial discharge mode, determining whether a difference between the voltage values ​​of the first battery pack and the second battery pack is less than a second voltage threshold, and in response to the difference being less than the second voltage threshold, controlling the switching module to switch the discharge mode of the power battery system to the parallel discharge mode;

[0014] In which, the initial voltage of the first battery group is greater than the initial voltage of the second battery group, and the switching module includes a unidirectional diode and a switching switch connected in parallel at both ends of the unidirectional diode; in the partial discharge mode, the first battery group and the second battery group are connected in parallel to the load end, the positive electrode of the second battery group is connected to the positive electrode of the load end through the unidirectional diode, and the first battery group supplies power to the load; in the parallel discharge mode, the first battery group and the second battery group are connected in parallel to the load end, the switching switch in parallel with the unidirectional diode is closed, and the first battery group and the second battery group jointly supply power to the load.

[0015] In a second aspect, the present application provides a power battery system, comprising a control module, a first battery pack, a second battery pack, and a switching module, wherein an initial voltage of the first battery pack is greater than an initial voltage of the second battery pack, the switching module comprises a unidirectional diode and a switching switch connected in parallel at both ends of the unidirectional diode, and the switching module operates under the control of the control module to switch a discharge mode of the power battery system; in a partial discharge mode, the first battery pack and the second battery pack are connected in parallel to a load end, the positive electrode of the second battery pack is connected to the positive electrode of the load end through the unidirectional diode, and the first battery pack supplies power to the load; in a parallel discharge mode, the first battery pack and the second battery pack are connected in parallel to the load end, the switching switch connected in parallel to the unidirectional diode is closed, and the first battery pack and the second battery pack jointly supply power to the load;

[0016] The control module includes:

[0017] a voltage data acquisition submodule, configured to acquire voltage values ​​of the first battery pack and the second battery pack when an upper high voltage request instruction is detected;

[0018] a voltage difference determination submodule configured to determine whether a voltage difference between the first battery pack and the second battery pack is less than a first voltage threshold; in response to the difference being less than the first voltage threshold, executing the contents executed by the parallel discharge control submodule; and in response to the difference being greater than or equal to the first voltage threshold, executing the contents executed by the partial discharge control submodule;

[0019] a parallel discharge control submodule, configured to control the power battery system to enter a parallel discharge mode in response to the difference being less than a first voltage threshold;

[0020] a partial discharge control submodule, configured to control the power battery system to enter a partial discharge mode in response to the difference being greater than or equal to a first voltage threshold;

[0021] The mode switching submodule is configured to determine whether the difference between the voltage values ​​of the first battery pack and the second battery pack is less than a second voltage threshold during the partial discharge mode, and in response to the difference being less than the second voltage threshold, control the switching module to switch the discharge mode of the power battery system to the parallel discharge mode.

[0022] In a third aspect, the present application provides an electronic device, comprising:

[0023] at least one processor; and

[0024] a memory communicatively connected to the at least one processor; wherein,

[0025] The memory stores a computer program that can be executed by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the power battery system discharge control method described in the first aspect of the present application.

[0026] In a fourth aspect, the present application provides a computer-readable storage medium storing computer instructions, wherein the computer instructions are used to enable a processor to implement the power battery system discharge control method described in the first aspect of the present application when executed.

[0027] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present application, nor is it intended to limit the scope of the present application. Other features of the present application will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The following is a brief introduction to the drawings required for describing the embodiments.

[0029] FIG1 is a schematic structural diagram of a power battery system provided in Example 1 of the present application;

[0030] FIG2 is a circuit diagram of a power battery system provided in Example 1 of the present application;

[0031] FIG3 is a flow chart of a method for controlling discharge of a power battery system provided in Example 1 of the present application;

[0032] FIG4 is a circuit diagram of a power battery system in parallel discharge mode provided in Example 1 of the present application;

[0033] FIG5 is a circuit diagram of a power battery system in a partial discharge mode provided in Example 1 of the present application;

[0034] FIG6 is a simplified diagram of a circuit connection method of a partial discharge mode provided in Example 1 of the present application;

[0035] 7A is a schematic diagram of a voltage variation trend of a branch where a first battery pack and a second battery pack are located in a partial discharge mode provided in Example 1 of the present application;

[0036] 7B is a schematic diagram of a current variation trend of a branch where a first battery pack and a second battery pack are located in a partial discharge mode provided in Example 1 of the present application;

[0037] FIG8 is a circuit diagram of another power battery system provided in Example 1 of the present application;

[0038] FIG9 is a circuit diagram of a pre-charging circuit provided in Example 1 of the present application;

[0039] FIG10 is a circuit diagram of another power battery system provided in Example 1 of the present application;

[0040] FIG11 is a circuit diagram of a power battery system in series charging mode provided in Example 1 of the present application;

[0041] FIG12 is a flow chart of a method for controlling discharge of a power battery system provided in Example 2 of the present application;

[0042] FIG13 is a schematic structural diagram of a control module provided in Example 3 of the present application;

[0043] FIG14 is a schematic structural diagram of an electronic device provided in Example 4 of the present application. DETAILED DESCRIPTION

[0044] The following will describe the technical solutions in the embodiments of this application in conjunction with the drawings in the embodiments of this application. The embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

[0045] Example 1

[0046] Embodiment 1 of the present application provides a method for controlling discharge of a power battery system. This embodiment is applicable to controlling the discharge mode of a battery in a power battery system. The method can be executed by a control module in the power battery system. The control module can be implemented in the form of hardware and / or software, and the control module can be configured in an electronic device.

[0047] This application proposes a new power battery system, and cooperates with a specific power battery system discharge control method to achieve partial discharge and parallel discharge, maintaining the consistency of different battery packs.

[0048] Figure 1 is a structural schematic diagram of a power battery system, and Figure 2 is a circuit diagram of a power battery system. As shown in Figures 1 and 2, the power battery system includes a first battery group 110, a second battery group 120, a switching module 130 and a control module 140 (not shown in Figure 2). The first battery group 110 and the second battery group 120 are both connected to the switching module 130, and the switching module 130 is connected to the control module 140. The control module 140 is used to control the action of the switching module 130 to switch the circuit connection mode of the power battery system, that is, to switch the discharge mode of the battery to the load. As shown in FIG2 , HV+ and HV- are the positive and negative electrodes of the load terminal, respectively. The switching module 130 includes a one-way diode D1 and a switch connected in parallel across the one-way diode D1, namely, a fifth switch RL5. The switching module 130 also includes a third switch RL3 and a sixth switch RL6. The first end of the third switch RL3 is connected to the positive electrode of the first battery pack 110, and the second end of the third switch RL3 is connected to the positive electrode of the load terminal. The first end of the sixth switch RL6 is connected to the negative electrode of the first battery pack 110, and the second end of the sixth switch RL6 is connected to the negative electrode of the second battery pack 120 and the negative electrode of the load terminal. The anode of the one-way diode D1 is connected to the positive electrode of the second battery pack 120, and the cathode of the one-way diode D1 is connected to the second end of the third switch RL3.

[0049] As shown in Figure 2, the power battery system also includes fuse Fuse1 and fuse Fuse2. Fuse Fuse1 is connected in series to the wire connected to the positive pole of the first battery pack 110, and fuse Fuse2 is connected in series to the wire connected to the positive pole of the second battery pack 120. The fuse plays a role in current limiting protection. When the current in the circuit is too large, the fuse burns out and disconnects the circuit.

[0050] As shown in FIG2 , the switching module 130 further includes a fourth switch RL4 . A first end of the fourth switch RL4 is connected to a second end of the sixth switch RL6 , and a second end of the fourth switch RL4 is connected to the negative electrode HV− of the load terminal. The fourth switch RL4 can function as a main grounding switch and is a normally closed switch.

[0051] The above switching switch may be a relay switch, and a control end of the relay switch is connected to the control module 140 .

[0052] In this embodiment, a battery pack may include one or more batteries, which is not limited in this application.

[0053] FIG3 is a flow chart of a power battery system discharge control method provided in the first embodiment of the present application. The power battery system discharge control method is applied to the control module 140 in the power battery system. As shown in FIG3 , the power battery system discharge control method includes:

[0054] S301 : When a high voltage request instruction is detected, obtain voltage values ​​of a first battery pack and a second battery pack.

[0055] In this embodiment, the control module has functions such as signal transmission and reception, information processing and logic control. Taking electric vehicles as an example, the control module may include a vehicle control unit (VCU) and a battery management system (BMS).

[0056] The VCU generates a high-voltage request signal when power is needed for the vehicle's loads. For example, when the VCU detects an accelerator pedal signal, it generates a high-voltage request signal and sends it to the BMS. The VCU is the core electronic control unit that makes vehicle control decisions. It collects signals from the accelerator pedal, gear position, and brake pedal, as well as monitors vehicle status information such as speed and temperature.

[0057] BMS can be used to intelligently manage and maintain multiple battery cells. It can monitor the parameter information of the battery pack and the power consumption data of the entire vehicle load. When the BMS receives a high-voltage request instruction, it obtains the first voltage value of the first battery pack and the second voltage value of the second battery pack.

[0058] The initial voltage of the first battery group is greater than the initial voltage of the second battery group, that is, the voltage consistency between the first battery group and the second battery group is poor.

[0059] S302: Determine whether a difference between the voltage values ​​of the first battery pack and the second battery pack is less than a first voltage threshold.

[0060] When the upper high voltage request instruction is detected, it is necessary to power the load. Taking electric vehicles as an example, the control module can control the vehicle state to change to the driving state. In the driving state, the battery pack is required to power the entire vehicle load, that is, the battery pack is in a discharging state. The discharge mode of the battery pack for the entire vehicle load includes a partial discharge mode and a parallel discharge mode. It is necessary to determine which discharge mode is suitable for entering under the current battery state, for example, whether the difference between the voltage values ​​of the first battery pack and the second battery pack is less than the first voltage threshold, that is, whether the difference between the voltage values ​​of the first battery pack and the second battery pack is large. If the difference between the voltage values ​​of the first battery pack and the second battery pack is less than the first voltage threshold, execute S303. If the difference between the voltage values ​​of the first battery pack and the second battery pack is greater than or equal to the first voltage threshold, execute S304.

[0061] The first voltage threshold may be 5V.

[0062] S303: Control the power battery system to enter a parallel discharge mode.

[0063] When the voltage difference between the first and second battery packs is less than a first voltage threshold, indicating a small voltage difference, the power battery system is controlled to enter parallel discharge mode. In parallel discharge mode, the two battery packs are connected in parallel to the load, and the switch connected in parallel with the one-way diode is closed, so that the two battery packs jointly power the load.

[0064] When the power battery system enters the parallel discharge mode, the control module controls the switching module to switch the circuit connection mode. In the circuit diagram shown in Figure 2, the control closes the third switch RL3, the fifth switch RL5, and the sixth switch RL6. At this time, the switch connected in parallel with the unidirectional diode D1 (i.e., the fifth switch RL5) is in a closed state, and the unidirectional diode D1 is short-circuited, resulting in a circuit diagram as shown in Figure 4. Figure 4 is a circuit diagram of a power battery system in parallel discharge mode. The first battery group 110 and the second battery group 120 are connected in parallel to the load end and jointly power the load. When the difference between the voltage values ​​of the first battery group and the second battery group is small, the two battery groups discharge the load together, which is beneficial to the consistency of different battery groups.

[0065] S304: Control the power battery system to enter a partial discharge mode.

[0066] When the voltage difference between the first and second battery packs is greater than or equal to a first voltage threshold, indicating a significant voltage difference, the power battery system is controlled to enter partial discharge mode. In partial discharge mode, the two battery packs are connected in parallel to the load terminal, with the positive terminal of the second battery pack connected to the positive terminal of the load terminal via a one-way diode. Only the first battery pack supplies power to the load.

[0067] When the power battery system enters partial discharge mode, the control module controls the switching module to switch the circuit connection mode. In the circuit diagram shown in Figure 2, the third switching switch RL3 is closed, the fifth switching switch RL5 is opened, and the sixth switching switch RL6 is closed, resulting in the circuit diagram shown in Figure 5. Figure 5 is a circuit diagram of a power battery system in partial discharge mode, which allows the first battery pack 110 to discharge the load alone. When the voltage difference between the first battery pack 110 and the second battery pack 120 is large, a simplified diagram of the circuit connection mode in partial discharge mode is shown in Figure 6. During partial discharge, when only the first battery pack 110 is discharging, the cathode voltage of the unidirectional diode D1 is higher than the anode voltage because the voltage of the first battery pack 110 is higher than the voltage of the second battery pack 120. That is, the voltage at point C in Figure 6 is higher than the voltage at point B. At this time, the unidirectional diode D1 does not conduct, and only the first battery pack 110 supplies power to the load, indicating that the power battery system enters partial discharge mode. In addition to controlling the entry into partial discharge mode, the unidirectional diode D1 also prevents the higher-voltage first battery pack 110 from charging the lower-voltage second battery pack 120.

[0068] S305 : During the partial discharge mode, if the difference between the voltage values ​​of the first battery group and the second battery group is less than a second voltage threshold, control the power battery system to switch to the parallel discharge mode.

[0069] In partial discharge mode, the first battery pack alone continuously supplies power to the load. Without intervention, the voltage and current trends of the branches containing the first and second battery packs are shown in Figures 7A and 7B, respectively. Figure 7A is a schematic diagram of the voltage change trend of the branches containing the first and second battery packs in partial discharge mode, and Figure 7B is a schematic diagram of the current change trend of the branches containing the first and second battery packs in partial discharge mode. In Figures 7A and 7B, the branch containing the first battery pack is branch 1, and the branch containing the second battery pack is branch 2. According to the time-voltage curves and time-current curves of the two branches, it can be seen that the initial voltage of branch 1 is higher than that of branch 2. In the first 425 seconds, only branch 1 discharges, the voltage of branch 1 gradually decreases, the discharge current of branch 2 is zero, and the voltage remains unchanged. From 425 to 925 seconds, the voltage of branch 1 is lower than that of branch 2, the unidirectional diode conducts, branch 2 participates in the discharge, the current of branch 1 decreases, and the current of branch 2 increases. After 925 seconds, the voltage states of the two branches are similar and the output current is the same. Then, in the partial discharge mode, if no intervention is made, since the first battery pack continues to supply power to the load alone, the voltage of the first battery pack will become lower and lower, and the difference between the voltage value of the first battery pack and the second battery pack will also become smaller and smaller. When the difference between the voltage values ​​of the first battery pack and the second battery pack is reduced to meet the conduction condition of the one-way diode, the second battery pack supplies power to the load through the one-way diode. After the one-way diode is turned on, the one-way diode will work with load for a long period of time, which will increase the system heat and affect the system energy consumption, and also affect the service life of the one-way diode.

[0070] In order to avoid the unidirectional diode from working under load for a long time, during the partial discharge mode, if the difference between the voltage values ​​of the first battery group and the second battery group is less than the second voltage threshold, it is considered that the voltages of the first battery group and the second battery group are close. At this time, the power battery system is controlled to switch to the parallel discharge mode, that is, the first battery group and the second battery group are discharged together. In the parallel discharge mode, the unidirectional diode is short-circuited, which can avoid the unidirectional diode from working under load for a long time and is also beneficial to the consistency of different battery packs.

[0071] The system load usually has a load capacitor. Taking electric vehicles as an example, the entire vehicle load usually has a load capacitor. When power is supplied to the entire vehicle load, if the entire vehicle load is directly connected and the load capacitor is turned on, the voltage difference between the power battery and the load capacitor can reach hundreds of volts, which is equivalent to a direct short circuit and can easily cause serious damage to the entire load capacitor. Therefore, in an optional embodiment of the present application, based on the circuit diagram of the power battery system shown in Figure 2, the switching module also includes a first switching switch RL1, a second switching switch RL2 and a pre-charging resistor R1, resulting in a circuit diagram as shown in Figure 8. Figure 8 is a circuit diagram of another power battery system, wherein the first end of the first switching switch RL1 is connected to the second end of the third switching switch RL3, and the second end of the first switching switch RL1 is connected to the positive electrode HV+ of the load end. The pre-charging resistor R1 and the second switching switch RL2 are connected in series between the second end of the third switching switch RL3 and the positive electrode HV+ of the load end. Figure 9 is a circuit diagram of a pre-charge circuit. Taking the case of supplying power to a load in partial discharge mode as an example, after closing the third switch RL3, opening the fifth switch RL5, and closing the sixth switch RL6, the first switch RL1 is opened and the second switch RL2 is closed to form a pre-charge circuit to pre-charge the load capacitance of the load. When the voltage of the load capacitance reaches a preset voltage value, the first switch RL1 is closed and the second switch RL2 is opened to officially supply power to the load.

[0072] In another optional embodiment, the power battery system also includes a series charging mode. Based on the power battery system circuit diagram shown in Figure 8, the switching module further includes a seventh switch RL7 and an eighth switch RL8. Figure 10 shows a circuit diagram of yet another power battery system. The first end of the eighth switch RL8 is connected to the positive terminal DC+ of the charging terminal, and the second end of the eighth switch RL8 is connected to the positive terminal of the first battery pack 110. The negative terminal of the first battery pack 110 is connected to the first end of the seventh switch RL7, and the second end of the seventh switch RL7 is connected to the positive terminal of the second battery pack 120. The negative terminal of the second battery pack 120 is connected to the negative terminal HV- of the load terminal and the negative terminal DC- of the charging terminal. The first end of the third switch RL3 is connected to the second end of the eighth switch RL8, and the second end of the third switch RL3 is connected to the first end of the fifth switch RL5, and the second end of the fifth switch RL5 is connected to the positive terminal of the second battery pack 120. The first end of the sixth switch RL6 is connected to the negative terminal of the first battery pack 110, and the second end of the sixth switch RL6 is connected to the negative terminal HV- of the load terminal.

[0073] In series charging mode, in the circuit shown in Figure 10, the fifth switch RL5 and the first switch RL1 are controlled to close, the second switch RL2 is opened, the third switch RL3 is opened, the sixth switch RL6 is opened, and then the seventh switch RL7 and the eighth switch RL8 are closed, entering series charging mode. This results in the circuit shown in Figure 11, which is a circuit diagram of a power battery system in series charging mode. In series charging mode, two battery packs are connected in series to the charging terminal, with the positive electrode of the first battery pack connected to the positive electrode of the charging terminal, and the line between the first and second battery packs is connected to the load terminal. The charging current flows from the positive electrode of the charging terminal to the first battery pack. After flowing out of the first battery pack, the charging current can be diverted to the second battery pack and the load, thus supplying power to the load. Therefore, the series connection of the first and second battery packs achieves fast charging and can also supply power to the load. In Figure 11, the solid line represents the charging circuit, and the dashed line represents the portion of the power supply circuit that is used independently and not shared with the charging circuit. This mode allows high-voltage fast charging while supplying low-voltage power to the load, meeting the power supply needs of the load in multiple scenarios.

[0074] Taking electric vehicles as an example, the battery pack can be charged through a charging pile. When the electric vehicle interacts with the charging pile, the control module identifies the charging category of the charging pile. When the control module identifies that the charging category of the charging pile is fast charging (for example, the charging terminal voltage is high voltage, about 550V-930V), the control module controls the switching module to control the power battery system to enter the series charging mode. In the series charging mode, the two battery packs are connected in series to the charging terminal, the positive electrode of the first battery pack is connected to the positive electrode of the charging terminal, and the first battery pack and the second battery pack are charged in series to achieve high-voltage super-fast charging. In addition, the line between the first battery pack and the second battery pack is connected to the vehicle load end of the electric vehicle to supply power to the vehicle load (for example, the voltage required by the vehicle load is about 230V-450V). Then, after the charging current flows out of the first battery pack, it can be diverted to the second battery pack and the vehicle load to supply power to the vehicle load. Among them, during fast charging, the power consumption of the vehicle load is mainly the power used by the air-conditioning compressor (for heating or cooling the cockpit and battery pack) and the cockpit.

[0075] Furthermore, in this series charging mode, the charging current flowing from the first battery pack can be diverted to the second battery pack and the load. This load diversion causes the charging current of the second battery pack to be less than that of the first battery pack. Therefore, the first battery pack is fully charged before the second battery pack. Since the two battery packs are charged in series, when the first battery pack is fully charged, the control module controls the switching module to disconnect the charging terminal, stopping charging. Thus, after the series charging is completed, the voltage of the first battery pack is higher than that of the second battery pack, resulting in inconsistent battery pack voltages. Therefore, during the subsequent discharge process, the power battery system discharge control method provided in this embodiment can resolve this problem of inconsistent battery pack voltages.

[0076] After the first and second battery packs are quickly charged, when the power battery system needs to enter a certain discharge mode, the control module can control the switch used in the series charging mode to be disconnected, and then control the switch used in the battery discharge mode to be switched to be closed.

[0077] The power battery system of the present application includes a control module, a first battery pack, a second battery pack and a switching module. By selecting two battery packs, it can meet the high-voltage fast charging requirements; in addition, by designing a unidirectional diode between the positive pole of the second battery pack and the positive pole of the load end, and connecting a switching switch in parallel at both ends of the unidirectional diode, the discharge mode and the consistency of the two battery packs can be regulated by the conduction characteristics of the unidirectional diode and the opening and closing of the switching switch, thereby meeting the low-voltage load power supply requirements.

[0078] In addition, the initial voltage of the first battery group is greater than the initial voltage of the second battery group. When entering the partial discharge mode, since the first battery group continues to supply power to the load alone, its voltage value becomes smaller and smaller, and the difference between the voltage value of the first battery group and the second battery group also becomes smaller and smaller. When the difference between the voltage values ​​of the first battery group and the second battery group is small enough to meet the automatic conduction condition of the one-way diode, the first battery group continues to supply power to the load. After the one-way diode is turned on, the second battery group supplies power to the load through the one-way diode. At this time, the one-way diode will work under load, which not only increases the system heat due to increased energy consumption, but also affects the service life of the one-way diode. On this basis, in the partial discharge mode, the difference between the voltage values ​​of the first battery group and the second battery group and the second voltage threshold are judged twice. When the difference between the voltage values ​​of the first battery group and the second battery group is less than the second voltage threshold, the switching switch is closed to short-circuit the one-way diode, thereby avoiding the problems of increased heat and shortened service life caused by long-term automatic conduction of the one-way diode.

[0079] Example 2

[0080] Figure 12 is a flow chart of a power battery system discharge control method provided by Example 2 of this application. This embodiment of the application is optimized based on the above-mentioned Example 1. This embodiment is described using an electric vehicle as an example. As shown in Figure 12, the power battery system discharge control method includes:

[0081] S121 . When a high-voltage request instruction is detected, obtain voltage values ​​of the first battery pack and the second battery pack.

[0082] S122: Determine whether the difference between the voltage values ​​of the first battery pack and the second battery pack is less than a first voltage threshold.

[0083] If the voltage difference between the first battery group and the second battery group is less than the first voltage threshold, execute S123 ; if the voltage difference between the first battery group and the second battery group is greater than or equal to the first voltage threshold, execute S124 .

[0084] S123. Control the power battery system to enter a parallel discharge mode.

[0085] S124. Control the power battery system to enter a partial discharge mode.

[0086] S121-S124 in this embodiment are similar to S401-S404 in the first embodiment. For details, please refer to the relevant description in S401-S404 and will not be explained here.

[0087] S125. During the partial discharge mode, obtain a first current value of the branch where the first battery pack is located and a second current value of the branch where the second battery pack is located.

[0088] Whether in partial discharge mode or switching from partial discharge mode to parallel discharge mode, both battery packs are used to power the load, that is, the branch where the two battery packs are located is the power supply branch of the load. Therefore, the first current value of the branch where the first battery pack is located and the second current value of the branch where the second battery pack is located can be obtained to determine the size of the load current.

[0089] During the partial discharge mode, a first current value of the branch where the first battery pack is located and a second current value of the branch where the second battery pack is located may be monitored by the BMS.

[0090] S126: Determine whether the difference between the voltage values ​​of the first battery group and the second battery group is less than a second voltage threshold, and whether the sum of the first current value and the second current value is less than a preset current threshold.

[0091] If the voltage difference between the first battery pack and the second battery pack is less than the second voltage threshold, and the sum of the first current value and the second current value is less than the preset current threshold, S127 is executed. For the two determination conditions in S126, it is possible to first determine whether the voltage difference between the first battery pack and the second battery pack is less than the second voltage threshold. If the voltage difference between the first battery pack and the second battery pack is less than the second voltage threshold, it is then determined whether the sum of the first current value and the second current value is less than the preset current threshold.

[0092] During partial discharge mode, if no intervention is taken, when the voltage of the first battery pack is lower than that of the second battery pack, the one-way diode conducts, allowing the second battery pack to participate in the discharge. This means that the two battery packs are connected in parallel to supply power to the load. After the one-way diode conducts, it will continue to carry the load for an extended period, increasing system heat and affecting system energy consumption, as well as the service life of the one-way diode. To avoid this, consider short-circuiting the one-way diode when the voltages of the two battery packs are close to or equal, switching from partial discharge mode to parallel discharge mode.

[0093] To prevent the unidirectional diode from operating under load for a long time, during partial discharge mode, if the voltage difference between the first battery pack and the second battery pack is less than a second voltage threshold, indicating that the voltages of the first battery pack and the second battery pack are close, the power battery system can be switched to parallel discharge mode. In parallel discharge mode, the unidirectional diode is short-circuited, which can prevent the unidirectional diode from operating under load for a long time. Switching to parallel discharge mode when the voltage difference between the first battery pack and the second battery pack is less than the second voltage threshold also promotes consistency among different battery packs.

[0094] Regardless of whether only the first battery pack supplies power to the load (the second current value is 0 at this time), or the first battery pack and the second battery pack are connected in parallel to supply power to the entire vehicle load, the sum of the first current value and the second current value is the power consumption of the entire vehicle load. When the sum of the first current value and the second current value is less than the preset current threshold, it means that the power consumption of the entire vehicle load is small. In this case, it switches to the parallel discharge mode, that is, closing the switching switch in parallel with the unidirectional diode, which can avoid the electric shock and adhesion failure caused by closing the switching switch in parallel with the unidirectional diode when the load consumes a large current, thereby improving safety.

[0095] Therefore, when the difference between the voltage values ​​of the first battery pack and the second battery pack is less than the second voltage threshold, and the sum of the first current value and the second current value is less than the preset current threshold, the BMS can send a request instruction to the VCU to close the switching switch in parallel with the unidirectional diode (switch to the parallel discharge mode).

[0096] The preset current threshold can be calibrated according to actual conditions, for example, it can be 30A.

[0097] In summary, when the following three conditions are met at the same time, the BMS sends a request instruction to the VCU to close the switch.

[0098] 1) The current discharge mode of the power battery system is partial discharge mode;

[0099] 2) The difference between the voltage values ​​of the first battery pack and the second battery pack is less than a second voltage threshold;

[0100] 3) The sum of the first current value and the second current value is less than a preset current threshold.

[0101] In an optional embodiment, the second voltage threshold is less than the first voltage threshold. Considering that the real-time dynamic voltage of a battery during discharge is lower than its static voltage, when only the first battery pack is discharging (partial discharge mode), the real-time dynamic voltage of the first battery pack is lower than its static voltage. In order to make the static voltages of the first battery pack and the second battery pack close when the partial discharge mode is stopped and switched to parallel discharge, when the first battery pack is discharged until the difference between the voltage values ​​of the first battery pack and the second battery pack is less than the second voltage threshold, the power battery system is controlled to enter the parallel discharge mode, and the second voltage threshold is less than the first voltage threshold.

[0102] For example, before stopping the partial discharge mode and switching to parallel discharge, V1 static is the static voltage of the first battery group, V1 dynamic is the real-time dynamic voltage of the first battery group, and V2 static is the static voltage of the second battery group (the second battery group is not discharged). The real-time voltage difference between the first battery group and the second battery group currently detected is V1 dynamic - V2 static, while the actual static voltage difference between the first battery group and the second battery group is V1 static - V2 static. Since V1 dynamic < V1 static, V1 dynamic - V2 static < V1 static - V2 static, that is, the voltage difference between the static voltages of the first battery group and the second battery group is greater than the real-time voltage difference. If, when stopping the partial discharge mode and switching to parallel discharge, the situation where the static voltage is greater than the real-time dynamic voltage is not considered, the voltage difference between the static voltages of the first battery group and the second battery group will exceed the expected value. The first voltage threshold may be a reference value of the difference between the voltage values ​​of the first battery group and the second battery group when both the voltage values ​​of the first battery group and the second battery group are static voltages. The first voltage threshold may be a reference value of the difference between the voltage values ​​of the first battery group and the second battery group when only the voltage value of the second battery group is a static voltage. By setting the second voltage threshold to be smaller than the first voltage threshold, the voltage difference between the static voltages of the first battery group and the second battery group when the partial discharge mode is stopped may be further narrowed. When the difference between the voltage values ​​of the first battery group and the second battery group is smaller than the second voltage threshold, the partial discharge mode is stopped and switched to parallel discharge, which is more conducive to the consistency of different battery groups.

[0103] For example, the first voltage threshold may be 5 V, and the second voltage threshold may be 2-3 V. Specifically, the voltage thresholds may be set based on test data. For example, the reference value of the voltage difference may be determined based on the magnitude of the circulating current caused by the voltage difference between the first battery pack and the second battery pack. The reference value may also be set based on the conduction voltage of a one-way diode or actual needs, and this application is not limited thereto.

[0104] S127. Obtain vehicle status information.

[0105] When the VCU receives a request to close the switch connected in parallel with the one-way diode, it obtains vehicle status information. The vehicle status information can include signals such as the accelerator pedal, gear position, and brake pedal, as well as information such as vehicle speed and temperature.

[0106] S128. Determine, based on the vehicle status information, whether the vehicle status satisfies a preset condition for closing the switching switch.

[0107] The preset conditions can be conditions related to the vehicle's overall state, used to limit the current draw of the vehicle's load. For example, if the driver is constantly driving, the vehicle's overall load current may be consistently high. In this case, the BMS cannot directly close the switch connected in parallel with the one-way diode while under load, as this could cause contact adhesion and compromise driving safety. Therefore, upon receiving a request to close the switch, to maintain consistency among the various battery packs while ensuring vehicle safety, the VCU obtains the vehicle's overall state and determines whether the preset conditions for closing the switch are met. If so, the process proceeds to S129. If not, a closing failure signal is sent to the BMS.

[0108] In an optional embodiment, the preset conditions are: the vehicle gear is in neutral and the vehicle speed is less than the preset speed, or the vehicle gear is in parking gear, or the vehicle gear is any one of the forward gear and reverse gear and the vehicle speed is less than the preset speed, and the automatic parking function is activated, or the vehicle gear is any one of the forward gear and reverse gear and the vehicle speed is less than the preset speed, and the ratio of the brake pedal stroke to the preset stroke is greater than the preset ratio.

[0109] That is, as long as the vehicle state meets the preset conditions of any closed switch, the switch can be closed. Among them, the preset vehicle speed is a relatively small speed, such as 5km / h. When the vehicle gear is in neutral and the speed is less than the preset speed, the load current is relatively small; the brake pedal is a pedal used to limit power and slow down the vehicle to stop. The ratio of the brake pedal stroke to the preset stroke is greater than the preset ratio (i.e., the braking stage). For example, the preset ratio can be 50%, indicating that the vehicle's braking power is relatively small and the braking friction is relatively large (the vehicle speed is slow). The vehicle load power consumption is relatively small, and the vehicle load current is relatively small.

[0110] When the vehicle's overall state meets the aforementioned conditions for closing the transfer switch, it indicates that the vehicle's load current is low. Closing the transfer switch at this time can prevent the transfer switch from sticking when closed under high current, further improving safety when closing the transfer switch. When the VCU confirms that the vehicle is in a state of low load current, it can return a closing permission message to the BMS, allowing the transfer switch to be closed.

[0111] S129. Control the power battery system to switch to the parallel discharge mode.

[0112] When the BMS receives a message indicating it is allowed to close, it controls the switch connected in parallel with the one-way diode to close, switching the power battery system to parallel discharge mode. This allows the first and second battery packs to be connected in parallel to supply power to the vehicle load, ensuring consistency between the different battery packs while ensuring driving safety. Furthermore, closing the switch when the vehicle load current is low minimizes the impact on the vehicle load's power consumption, allowing the vehicle load to operate normally.

[0113] The permission-to-close message may be sent within a preset time period, which may be 100ms.

[0114] In an optional embodiment, when the power battery system is controlled to switch to the parallel discharge mode, the load current can also be limited to a preset current range, for example, the preset current range can be a current range within 10 A. Then, it is detected whether the switch connected in parallel with the one-way diode is in the closed state. If it is in the closed state, the load current limit is lifted.

[0115] Taking electric vehicles as an example, after the BMS controls the switch in the battery control circuit to close and detects that the switch is closed, it feeds back the switch closure signal to the VCU. Upon receiving the switch closure signal, the VCU removes the restriction on the vehicle load's current consumption. The switch is a switch with auxiliary contacts. The BMS detects the duty cycle of the pulse width modulation (PWM) wave of the switch and determines the state of the switch based on the PWM wave duty cycle. When the switch is not conducting (disconnected), the duty cycle is 0, and when it is conducting (closed), it is a fixed duty cycle.

[0116] The vehicle load is high-voltage components such as motors and air conditioners.

[0117] The VCU controls the power consumption of the vehicle's loads. For example, by requesting torque from the motor and sending available power to the air conditioner, the VCU can limit the motor and air conditioner power to ensure that the maximum current is less than the current limit. The current limit is calculated based on current battery information. This information can include battery charge, temperature, power, or current limit. The BMS can obtain this information and send it to the VCU, which then limits the current consumption of the vehicle's loads based on this information.

[0118] By limiting the vehicle load current during the switching stage, closing the switching switch under high current can be avoided, thereby further ensuring driving safety. On the other hand, limiting the load current can prevent the load current from increasing due to faults and other factors, which may affect the switching process.

[0119] Closing the switch is instantaneous (in milliseconds), typically completing within 30 milliseconds, with minimal impact on the vehicle's load. The time required from the BMS sending the request to close the switch to the VCU until the VCU removes the load current limit is typically around 1 second, minimizing the impact on load power consumption. The entire process requires no high-voltage shutdown, ensuring continuous power supply to the vehicle's loads.

[0120] In this embodiment, the switch is closed only when the difference between the voltages of the first and second battery packs is less than a second voltage threshold, the sum of the currents of the two branches is less than a preset current threshold, and the vehicle's overall state satisfies the switch closing conditions. This ensures that the switch is closed only when the vehicle's high-voltage loads are drawing low current, avoiding sticking failures caused by closing the switch under high current, thereby improving driving safety. Furthermore, the impact on the vehicle's overall load power consumption is minimal, allowing the vehicle's overall loads to operate normally.

[0121] Example 3

[0122] FIG1 is a schematic diagram of the structure of a power battery system provided in Example 3 of the present application. As shown in FIG1 , the power battery system includes: a control module 140, a first battery pack 110, a second battery pack 120, and a switching module 130. The initial voltage of the first battery pack 110 is greater than the initial voltage of the second battery pack 120. The switching module 130 includes a unidirectional diode and a switch connected in parallel at both ends of the unidirectional diode. The switching module 130 operates under the control of the control module 140 to switch the discharge mode of the power battery system. In the partial discharge mode, the first and second battery packs are connected in parallel to the load terminal, the positive electrode of the second battery pack 120 is connected to the positive electrode of the load terminal via the unidirectional diode, and the first battery pack 110 supplies power to the load. In the parallel discharge mode, the first and second battery packs are connected in parallel to the load terminal, the switch connected in parallel with the unidirectional diode is closed, and the first and second battery packs jointly supply power to the load.

[0123] As shown in FIG13 , the control module 140 includes: a voltage data acquisition submodule 141, configured to acquire the voltage values ​​of the first battery pack 110 and the second battery pack 120 when an upper high voltage request instruction is detected; a voltage difference judgment submodule 142, configured to judge whether the difference between the voltage values ​​of the first battery pack 110 and the second battery pack 120 is less than a first voltage threshold; if the difference is less than the first voltage threshold, the contents executed by the parallel discharge control submodule are executed; if the difference is greater than or equal to the first voltage threshold, the contents executed by the partial discharge control submodule are executed; a parallel discharge control submodule 143, configured to The power battery system is configured to enter a parallel discharge mode in response to the difference being less than a first voltage threshold; the partial discharge control submodule 144 is configured to control the power battery system to enter a partial discharge mode in response to the difference being greater than or equal to a first voltage threshold; the mode switching submodule 145 is configured to determine whether the difference between the voltage values ​​of the first battery group 110 and the second battery group 120 is less than a second voltage threshold during the partial discharge mode, and control the switching module 130 to switch the discharge mode of the power battery system to a parallel discharge mode in response to the difference being less than the second voltage threshold.

[0124] In an optional embodiment, the mode switching submodule 145 includes: a current value acquisition unit configured to acquire, during the partial discharge mode, a first current value of the branch where the first battery pack 110 is located and a second current value of the branch where the second battery pack 120 is located; a current sum value determination unit configured to determine whether the difference is less than a second voltage threshold and whether the sum of the first and second current values ​​is less than a preset current threshold; if the difference is less than the second voltage threshold and the sum is less than the preset current threshold, executing the contents executed by the mode switching unit; and a mode switching unit configured to control the switching module 130 to switch the discharge mode of the power battery system to a parallel discharge mode in response to the difference being less than the second voltage threshold and the sum being less than the preset current threshold. In an optional embodiment, the power battery is used in an electric vehicle, and the control module 140 further includes: a vehicle status information acquisition submodule configured to acquire vehicle status information; and a condition determination submodule configured to determine, based on the vehicle status information, whether the vehicle status satisfies a preset condition for closing the switch; if the preset condition is satisfied, executing the contents executed by the mode switching unit. In an optional embodiment, the preset condition is one of the following: the vehicle gear is in neutral and the vehicle speed is less than the preset speed; the vehicle gear is in parking gear; the vehicle gear is any one of the forward gear and reverse gear and the vehicle speed is less than the preset speed, and the automatic parking function is activated; the vehicle gear is any one of the forward gear and reverse gear and the vehicle speed is less than the preset speed, and the ratio of the brake pedal stroke to the preset stroke is greater than the preset ratio.

[0125] In an optional embodiment, the control module 140 further includes: a current limiting submodule, configured to limit the power consumption current of the load within a preset current range when the mode switching submodule 145 controls the switching module 130 to switch the discharge mode of the power battery system to the parallel discharge mode.

[0126] In an optional embodiment, the control module 140 also includes: a switching switch state detection submodule, configured to detect whether the switching switch connected in parallel with the unidirectional diode is in a closed state; if the switching switch is in a closed state, executing the content executed by the restriction cancellation submodule; and a restriction cancellation submodule, configured to cancel the restriction on the power current of the load in response to the switching switch being in a closed state.

[0127] In an optional embodiment, the second voltage threshold is lower than the first voltage threshold.

[0128] In an optional embodiment, a series charging mode is further included. In the series charging mode, the first battery group 110 and the second battery group 120 are connected in series to the charging end, wherein the positive pole of the first battery group 110 is connected to the positive pole of the charging end; and the line between the first battery group 110 and the second battery group 120 is connected to the load end to supply power to the load.

[0129] The power battery system provided in the embodiments of the present application can execute the power battery system discharge control method provided in any embodiment of the present application, and has the corresponding functional modules and effects of the execution method.

[0130] Example 4

[0131] FIG14 shows a block diagram of an electronic device 40 that can be used to implement embodiments of the present application. The electronic device is intended to represent any form of digital computer, such as a laptop computer, desktop computer, workstation, personal digital assistant, server, blade server, mainframe computer, and other suitable computers. The components shown herein, their connections and relationships, and their functions are provided as examples only and are not intended to limit the implementation of the present application as described and / or claimed herein.

[0132] As shown in Figure 14, the electronic device 40 includes at least one processor 41, and a memory connected to the at least one processor 41, such as a read-only memory (ROM) 42, a random access memory (RAM) 43, etc., wherein the memory stores a computer program that can be executed by the at least one processor, and the processor 41 can perform any appropriate action and processing according to the computer program stored in the read-only memory (ROM) 42 or the computer program loaded from the storage unit 48 to the random access memory (RAM) 43. In the RAM 43, one or more programs and data required for the operation of the electronic device 40 can also be stored. The processor 41, ROM 42 and RAM 43 are connected to each other via a bus 44. An input / output (I / O) interface 45 is also connected to the bus 44.

[0133] Multiple components in the electronic device 40 are connected to the I / O interface 45, including an input unit 46, such as a keyboard, a mouse, etc.; an output unit 47, such as any type of display, a speaker, etc.; a storage unit 48, such as a magnetic disk, an optical disk, etc.; and a communication unit 49, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 49 allows the electronic device 40 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks.

[0134] The processor 41 can be any general-purpose and / or specialized processing component with processing and computing capabilities. Some examples of the processor 41 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), any dedicated artificial intelligence (AI) computing chip, any processor that runs a machine learning model algorithm, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. The processor 41 executes any of the methods and processes described above, such as the power battery system discharge control method.

[0135] In some embodiments, the power battery system discharge control method can be implemented as a computer program, which is tangibly contained in a computer-readable storage medium, such as a storage unit 48. In some embodiments, part or all of the computer program can be loaded and / or installed on the electronic device 40 via the ROM 42 and / or the communication unit 49. When the computer program is loaded into the RAM 43 and executed by the processor 41, one or more steps of the power battery system discharge control method described above can be performed. Alternatively, in other embodiments, the processor 41 can be configured to execute the power battery system discharge control method in any other appropriate manner (for example, by means of firmware).

[0136] Various embodiments of the systems and techniques described above can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These embodiments can include being implemented in one or more computer programs that are executable and / or interpreted on a programmable system that includes at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0137] Computer programs for implementing the methods of the present application may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when the computer program is executed by the processor, the functions / operations specified in the flowcharts and / or block diagrams are implemented. The computer program may be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0138] In the context of the present application, a computer-readable storage medium can be a tangible medium that can contain or store a computer program for use by an instruction execution system, device or equipment or used in combination with an instruction execution system, device or equipment. A computer-readable storage medium can include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium can be a machine-readable signal medium. A more specific example of a machine-readable storage medium can include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM) or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0139] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a cathode ray tube (CRT) or a liquid crystal display (LCD) monitor) configured to display information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user can provide input to the electronic device. Other types of devices can also be configured to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and the input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0140] The systems and techniques described herein can be implemented in a computing system that includes back-end components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes front-end components (e.g., a user computer with a graphical user interface or web browser through which a user can interact with embodiments of the systems and techniques described herein), or a computing system that includes any combination of such back-end components, middleware components, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0141] A computing system may include a client and a server. The client and server are generally remote from each other and typically interact via a communication network. This client-server relationship is established by running computer programs on the respective computers. The server may be a cloud server, also known as a cloud computing server or cloud host. This server is a host product within a cloud computing service ecosystem that addresses the management difficulties and limited scalability of traditional physical hosts and virtual private server (VPS) services.

Claims

1. A power battery system discharge control method, applied to a control module in a power battery system, The method comprises: When an upper high voltage request instruction is detected, obtaining voltage values ​​of a first battery pack and a second battery pack in the power battery system; Determining whether a difference between the voltage values ​​of the first battery group and the second battery group is less than a first voltage threshold; In response to the difference being less than a first voltage threshold, controlling the power battery system to enter a parallel discharge mode; In response to the difference being greater than or equal to a first voltage threshold, controlling the power battery system to enter a partial discharge mode; During the partial discharge mode, determining whether a difference between the voltage values ​​of the first battery group and the second battery group is less than a second voltage threshold; In response to the difference being less than a second voltage threshold, controlling a switching module in the power battery system to switch a discharge mode of the power battery system to a parallel discharge mode; Among them, the initial voltage of the first battery group is greater than the initial voltage of the second battery group, and the switching module includes a unidirectional diode and a switching switch connected in parallel at both ends of the unidirectional diode; in a partial discharge mode, the first battery group and the second battery group are connected in parallel to the load end, the positive electrode of the second battery group is connected to the positive electrode of the load end through the unidirectional diode, and the first battery group supplies power to the load; in a parallel discharge mode, the first battery group and the second battery group are connected in parallel to the load end, the switching switch connected in parallel with the unidirectional diode is closed, and the first battery group and the second battery group jointly supply power to the load.

2. The method of claim 1, wherein: In the partial discharge mode, in response to the difference being less than a second voltage threshold, controlling the switching module to switch the discharge mode of the power battery system to the parallel discharge mode includes: During the partial discharge mode, obtaining a first current value of a branch where the first battery group is located and a second current value of a branch where the second battery group is located; Determine whether the difference is less than a second voltage threshold, and whether the sum of the first current value and the second current value is less than a preset current threshold; In response to the difference being smaller than a second voltage threshold and the sum being smaller than a preset current threshold, the switching module is controlled to switch the discharge mode of the power battery system to a parallel discharge mode.

3. The method of claim 1, wherein: The power battery is applied to an electric vehicle, and before the switching module is controlled to switch the discharge mode of the power battery system to the parallel discharge mode, the power battery system further includes: Get vehicle status information; Determining whether the vehicle state satisfies a preset condition for closing the switch according to the vehicle state information; In response to satisfying the preset condition, the switching module is controlled to switch the discharge mode of the power battery system to the parallel discharge mode.

4. The method of claim 3, wherein: The preset condition is one of the following: The vehicle gear is in neutral and the speed is less than the preset speed; The vehicle gear position is the parking gear position; The vehicle is in either the forward or reverse gear and the vehicle speed is less than the preset speed, and the automatic parking function is activated; The vehicle gear is any one of the forward gear and the reverse gear and the vehicle speed is less than the preset vehicle speed, and the ratio of the brake pedal stroke to the preset stroke is greater than the preset ratio.

5. The method according to claim 1, when controlling the switching module to switch the discharge mode of the power battery system to the parallel discharge mode, further comprises: The power consumption of the load is limited within a preset current range.

6. The method according to claim 5, after limiting the current consumption of the load within a preset current range, further comprising: Detecting whether the switch connected in parallel with the unidirectional diode is in a closed state; In response to the switching switch being in a closed state, limiting the current consumption of the load is cancelled.

7. The method according to any one of claims 1 to 6, wherein: The second voltage threshold is lower than the first voltage threshold.

8. The method according to any one of claims 1 to 6, further comprising: The first battery group and the second battery group are connected in series to a charging end, wherein the positive electrode of the first battery group is connected to the positive electrode of the charging end; and the line between the first battery group and the second battery group is connected to the load end to supply power to the load.

9. A power battery system, comprising a control module, a first battery group, a second battery group and a switching module, wherein the initial voltage of the first battery group is greater than the initial voltage of the second battery group, the switching module comprises a unidirectional diode and a switching switch connected in parallel at both ends of the unidirectional diode, and the switching module operates under the control of the control module to switch the discharge mode of the power battery system; in a partial discharge mode, the first battery group and the second battery group are connected in parallel to a load end, the positive electrode of the second battery group is connected to the positive electrode of the load end through the unidirectional diode, and the first battery group supplies power to the load; in a parallel discharge mode, the first battery group and the second battery group are connected in parallel to the load end, the switching switch connected in parallel with the unidirectional diode is closed, and the first battery group and the second battery group jointly supply power to the load; The control module comprises: a voltage data acquisition submodule, configured to acquire voltage values ​​of the first battery pack and the second battery pack when an upper high voltage request instruction is detected; a voltage difference judgment submodule, configured to judge whether the difference between the voltage values ​​of the first battery group and the second battery group is less than a first voltage threshold; in response to the difference being less than the first voltage threshold, executing the content executed by the parallel discharge control submodule; in response to the difference being greater than or equal to the first voltage threshold, executing the content executed by the partial discharge control submodule; a parallel discharge control submodule, configured to control the power battery system to enter a parallel discharge mode in response to the difference being less than a first voltage threshold; a partial discharge control submodule, configured to control the power battery system to enter a partial discharge mode in response to the difference being greater than or equal to a first voltage threshold; The mode switching submodule is configured to determine whether the difference between the voltage values ​​of the first battery group and the second battery group is less than a second voltage threshold during the partial discharge mode, and in response to the difference being less than the second voltage threshold, control the switching module to switch the discharge mode of the power battery system to the parallel discharge mode.

10. An electronic device, comprising: at least one processor; as well as a memory communicatively connected to the at least one processor; wherein, The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the power battery system discharge control method according to any one of claims 1 to 8.

11. A computer-readable storage medium storing computer instructions, wherein: The computer instructions are used to enable a processor to implement the power battery system discharge control method according to any one of claims 1 to 8 when executed.

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