Immersed liquid-cooled battery pack

Abstract

The present invention relates to the technical field of thermal management of battery packs, and in particular to an immersion liquid-cooled battery pack, which includes a plurality of liquid-cooling working areas, in which a plurality of groups of two charging modules are arranged in parallel as a group, and the two charging modules of a single group are connected through an electromagnetic reversing valve. Through the dual-mode control of a control unit, the liquid cooling control can be matched with different capacity fluctuation states of the charging modules to maintain the service life and use stability of the battery. Through the dual control modes of a first mode and a second mode, the capacity fluctuation states of different charging modules are matched while effectively controlling energy consumption, thereby effectively improving the overall capacity stability of the immersion liquid-cooled battery pack and avoiding the waste of liquid cooling energy caused by uneven distribution of cooling effect due to excessive capacity difference.

Description

Technical Field

[0001] The present invention relates to the technical field of battery pack thermal management, and in particular to an immersion liquid-cooled battery pack. Background Art

[0002] Generally, batteries that are cooled by liquid cooling are under the working conditions of fast charging and high-rate discharge, which will generate a lot of heat and gradually increase the temperature. When the temperature is too high, the working performance of the battery will decrease and the life will be reduced. In severe cases, thermal runaway may occur, endangering the safety of the battery. If the temperature is too low, the reaction rate inside the lithium-ion battery will be reduced, and the battery capacity will also be reduced. In addition, excessive temperature differences inside the battery or between battery cells will have an adverse effect on the performance of the battery. Therefore, in order to ensure that the liquid-cooled battery pack performs well, thermal management of the liquid-cooled battery pack is necessary.

[0003] For example, the prior art discloses an integrated thermal management system for a battery pack, including a temperature monitoring module for monitoring the temperature of the battery pack and the external temperature in real time when the battery is in working condition, collecting the detection results of the two at the same time, comparing the comparison results with the threshold value, and outputting alarm data; a data processing module for receiving and saving the alarm data, generating a temperature control strategy through the alarm data, and issuing the control strategy; a judgment module for receiving the control strategy, judging the control strategy according to historical data, and issuing corresponding execution instructions after determination; a thermal management module for receiving the execution instruction and controlling the corresponding temperature adjustment module to control the temperature of the battery pack so that the battery pack is within the normal temperature range; the temperature of the battery pack can be timely adjusted while detecting the battery temperature, which can effectively improve the service life of the battery.

[0004] However, the thermal management allocation of each battery in the above scheme is only based on temperature, and lacks analysis of the performance differences of the battery during use. It cannot effectively ensure the balance of thermal management, and thus cannot ensure the capacity stability of the battery pack. Summary of the invention

[0005] The purpose of the present invention is to provide an immersion liquid-cooled battery pack to solve the problem of lack of analysis on the performance differences of the battery in the use stage, inability to effectively ensure the balance of thermal management, and thus inability to ensure the capacity stability of the battery pack.

[0006] To this end, the present invention provides an immersion liquid-cooled battery pack, which includes a plurality of liquid-cooled working areas, in which a plurality of groups of charging modules are arranged in parallel with two charging modules as a group, and the coolant flows through each group of charging modules. The two charging modules of a single group are connected by an electromagnetic reversing valve. The immersion liquid-cooled battery pack also includes: a collection unit, a recording unit and a control unit.

[0007] The collection unit is used to collect the temperature and relative capacity of each charge and discharge cycle of the charging module;

[0008] The recording unit is configured to obtain, after any charge and discharge cycle, an absolute value of a difference between a relative capacity of each charge and discharge cycle of the charging module and a theoretical relative capacity as a fluctuation value, sum the fluctuation values ​​of each historical charge and discharge cycle as a fluctuation accumulation parameter, and sum the difference between the relative capacity of each historical charge and discharge cycle and the theoretical relative capacity as a fluctuation tendency parameter;

[0009] The control unit is provided with the following control modes for the liquid cooling working area,

[0010] In the first mode, the electromagnetic reversing valve is set to a two-way conduction state, and the coolant flow rate is adjusted to keep the charging module at a preset temperature. The enabling condition of the first mode is that the fluctuation cumulative parameters of each charging module in the liquid cooling working area are less than or equal to the corresponding threshold value;

[0011] In the second mode, the electromagnetic reversing valve is set to be unidirectionally conducted toward the charging module with a higher fluctuation accumulation parameter, and the coolant flow rate is adjusted to keep the charging module at a preset temperature, and the opening of the electromagnetic reversing valve is adjusted based on the difference in fluctuation accumulation parameters of each group of charging modules. The enabling condition of the second mode is that there is a charging module with a fluctuation accumulation parameter greater than a corresponding threshold in the liquid cooling working area, and the fluctuation tendency parameters of each charging module in the liquid cooling working area are greater than or equal to the corresponding threshold;

[0012] Furthermore, the control unit shuts down the corresponding charging module and its liquid cooling supply in response to the existence of a charging module whose fluctuation tendency parameter is less than a corresponding threshold value, or the existence of a charging module whose relative capacity does not meet the standards, and re-determines the enabling status of the control mode after shutdown.

[0013] As a preferred technical solution for the submerged liquid-cooled battery pack, the process in which the control unit adjusts the opening of the electromagnetic reversing valve based on the difference in the fluctuation accumulation parameter in the second mode includes:

[0014] Determine the opening of the electromagnetic reversing valve between the charging modules based on the fluctuation accumulation parameters of each charging module in a single group;

[0015] The opening degree of the electromagnetic reversing valve is positively correlated with the fluctuation accumulation parameter of the charging module on the outlet side of the electromagnetic reversing valve.

[0016] As a preferred technical solution for the immersed liquid-cooled battery pack, the control unit closes the electromagnetic reversing valve corresponding to the charging module while closing the charging module and its liquid cooling supply.

[0017] As a preferred technical solution for the immersion liquid-cooled battery pack, the recording unit stores theoretical relative capacities of the charging module at different liquid cooling levels and ambient temperatures.

[0018] As a preferred technical solution for the immersion liquid-cooled battery pack, the recording unit outputs an update requirement for the theoretical relative capacity of the charging module in response to the fluctuation tendency parameter being a positive value.

[0019] As a preferred technical solution for the immersion liquid-cooled battery pack, the charging module includes:

[0020] A cooling box and a plurality of batteries evenly distributed in the cooling box;

[0021] A battery bracket, disposed inside the cooling box and used for fixing the battery;

[0022] A liquid inlet pipe, used for introducing coolant into the cooling box;

[0023] The liquid outlet pipe is used to discharge the coolant out of the cooling box.

[0024] As a preferred technical solution for the immersion liquid-cooled battery pack, the recording unit characterizes the degree of liquid cooling through a liquid cooling characteristic value, and the liquid cooling characteristic value is determined by the temperature difference between the liquid outlet pipe and the liquid inlet pipe, and the amount of coolant in the corresponding charging module. The higher the liquid cooling characteristic value, the greater the corresponding degree of liquid cooling;

[0025] The liquid cooling characteristic value is positively correlated with the temperature difference between the liquid inlet pipe and the liquid outlet pipe, and the amount of coolant acting on the charging module.

[0026] As a preferred technical solution for the immersion liquid-cooled battery pack, a partition is provided between two charging modules of a single group of charging modules.

[0027] As the preferred technical solution for the immersed liquid-cooled battery pack, each liquid-cooled working area is provided with a coolant inlet and a coolant outlet, the upstream of the coolant inlet is connected to a water pump and a cooling tower in sequence, and the coolant inlet is provided with a control valve.

[0028] The beneficial effects of the present invention are:

[0029] The immersion liquid-cooled battery pack of the present invention can timely discover the capacity fluctuation of the battery through cumulative quantitative analysis of the battery capacity fluctuation, and adjust the liquid cooling mode based on the battery capacity stability to maintain the service life and usage stability of the battery. Through the dual control mode of the first mode and the second mode, the capacity fluctuation state of different charging modules can be matched while effectively controlling energy consumption, thereby effectively improving the overall capacity stability of the immersion liquid-cooled battery pack and avoiding the uneven distribution of cooling effect caused by excessive capacity differences and the resulting waste of liquid cooling energy.

[0030] Furthermore, the present invention enhances the heat exchange capacity between the modules through the design of the electromagnetic reversing valve, and the bidirectional conduction of the second electromagnetic reversing valve in the first mode facilitates the coolant to flow evenly and quickly to each charging module. In the second mode, by increasing the additional coolant flow in the charging module with larger capacity fluctuation, the turbulence of the coolant in the charging module with capacity fluctuation is increased, thereby improving the liquid cooling effect, ensuring that a better liquid cooling effect can improve the capacity stability of the charging module with capacity fluctuation, and by taking into account the control logic of the remaining charging modules at the same time, if there is a slight loss of coolant in a single group of charging modules, the temperature of the charging module can be maintained, and the liquid cooling effect on the charging module with capacity fluctuation can be better than that in the first mode, and specifically can improve the range and uniformity of the internal liquid cooling, thereby ensuring the capacity stability of the charging module, thereby improving the capacity stability of the entire liquid-cooled battery pack.

[0031] Furthermore, by introducing fluctuation accumulation parameters and fluctuation tendency parameters, the submerged liquid-cooled battery pack of the present invention can intelligently and dynamically adjust the coolant flow rate and turbulence, thereby optimizing the thermal management effect of the battery, improving capacity stability and extending battery life. At the same time, the precise control of the electromagnetic reversing valve makes the change of the flow path and flow rate of the coolant between different charging modules more flexible, enhancing the adaptability and efficiency of the system. In addition, the intelligent fault response mechanism and automatic adjustment function can achieve efficient and reliable cooling management, further improving the intelligence level and energy utilization efficiency of the system.

[0032] Furthermore, by introducing fluctuation accumulation parameters and fluctuation tendency parameters, the liquid-cooled battery pack can accurately adjust the coolant flow rate and turbulence according to the charging and discharging historical fluctuations and temperature changes of each charging module. The larger the fluctuation accumulation parameter, the higher the capacity instability of the charging module, while the fluctuation tendency parameter can reflect the capacity change trend of the module (whether it increases or decreases). This precise parameter judgment provides data support for the dynamic adjustment of the cooling system, so that it can efficiently respond to the battery working state and ensure that the temperature control of the charging module is maintained at the optimal level under different charging conditions.

[0033] Furthermore, in the second mode, the one-way opening function of the electromagnetic reversing valve effectively controls the flow direction of the coolant, ensuring that the turbulence of the coolant flowing through the charging module with large fluctuations is enhanced. By increasing the local turbulence, the heat exchange efficiency can be significantly enhanced, the temperature fluctuation can be reduced, and the negative impact of temperature changes on the battery capacity can be reduced. This helps to improve the capacity stability of the charging module, reduce the capacity attenuation caused by temperature fluctuations, and increase the cycle life of the battery.

[0034] Furthermore, the electromagnetic reversing valve in the present invention has a regulating function, which can automatically adjust the flow direction and flow size according to the fluctuation cumulative parameter differences of the charging module. When the fluctuations of some charging modules are large, the coolant increases the turbulence by changing the opening, increases the contact area between the coolant and the surface of the battery module, and thus optimizes the heat transfer efficiency. Through this intelligent control strategy, the coolant flow rate and turbulence can be accurately adjusted in a local area, so that the liquid cooling system can not only ensure the overall cooling effect, but also flexibly respond to the needs of different regions, further reducing energy waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a control block diagram of an immersion liquid-cooled battery pack in an embodiment of the present invention;

[0036] Figure 2 Schematic diagram of the operation of the submerged liquid-cooled battery pack in an embodiment of the present invention;

[0037] Figure 3 This is a schematic diagram of the structure of a single charging module in an embodiment of the present invention;

[0038] Figure 4 Schematic diagram of the structure of the charging module in an embodiment of the present invention.

[0039] In the figure: 1. Liquid cooling working area; 2. Charging module; 3. Solenoid reversing valve; 4. Partition; 5. Coolant inlet; 6. Coolant outlet; 7. Water pump; 8. Cooling tower; 9. Control valve; 10. Cooling box; 11. Battery; 12. Battery bracket; 13. Liquid inlet pipe. DETAILED DESCRIPTION

[0040] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0042] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0043] Please combine Figure 1-4 As shown, this embodiment provides an immersion liquid-cooled battery pack, which includes a plurality of liquid-cooled working areas 1, in which a plurality of groups of charging modules 2 are arranged in parallel with each other as a group, and the coolant flows through each group of charging modules 2. The two charging modules of a single group are connected by an electromagnetic reversing valve 3, and a partition 4 is provided between the two charging modules of a single group of charging modules. Each liquid-cooled working area is provided with a coolant inlet 5 and a coolant outlet 6, respectively, and the upstream of the coolant inlet 5 is connected to a water pump 7 and a cooling tower 8 in sequence, and the coolant inlet 5 is provided with a control valve 9. The charging module 2 includes: a cooling box 10 and a plurality of batteries 11 evenly distributed in the cooling box 10, a battery bracket 12 surrounded in the cooling box 10 for fixing the batteries 11, a liquid inlet pipe 13 for introducing the coolant into the cooling box 10, and a liquid outlet pipe (not shown in the figure, located on the side opposite to the liquid inlet pipe 13) for exporting the coolant to the outside of the cooling box 10. The charging modules can operate independently, and the liquid cooling systems of each charging module are independent of each other. When a charging module fails, it will not cause failures in other battery modules and maintain their normal operation. In implementation, the coolant can be circulated individually or multiple charging modules can be circulated together according to the liquid cooling configuration, thereby improving the flexibility of operation and maintenance.

[0044] On the basis of the above structure, in order to optimize the liquid cooling control based on capacity stability, the immersion liquid-cooled battery pack of this embodiment also includes a collection unit, a recording unit and a control unit. The collection unit is used to collect the temperature (determined by the average value of several thermocouples in the charging module) and the relative capacity of each charge and discharge cycle of the charging module; the recording unit is configured to obtain the absolute value of the difference between the relative capacity of each charge and discharge cycle of the charging module and the theoretical relative capacity as the fluctuation value, sum the fluctuation values ​​of each charge and discharge cycle in history as the fluctuation accumulation parameter, and sum the difference between the relative capacity of each charge and discharge cycle in history and the theoretical relative capacity as the fluctuation tendency parameter after any charge and discharge cycle ends;

[0045] The control unit has the following control modes for the liquid cooling working area:

[0046] In the first mode, the electromagnetic reversing valve is set to a two-way conduction state, and the coolant flow rate is adjusted to keep the charging module at a preset temperature. The enabling condition of the first mode is that the fluctuation cumulative parameters of each charging module in the liquid cooling working area are less than or equal to the corresponding threshold value;

[0047] In the second mode, the electromagnetic reversing valve is set to be unidirectionally conducted toward the charging module with a higher fluctuation accumulation parameter, and the coolant flow rate is adjusted to keep the charging module at a preset temperature, and the opening of the electromagnetic reversing valve is adjusted based on the difference in the fluctuation accumulation parameters of each group of charging modules. The enabling condition of the second mode is that there is a charging module with a fluctuation accumulation parameter greater than the corresponding threshold in the liquid cooling working area, and the fluctuation tendency parameters of each charging module in the liquid cooling working area are greater than or equal to the corresponding threshold;

[0048] Furthermore, in response to the existence of a charging module whose fluctuation tendency parameter is less than the corresponding threshold value, or the existence of a charging module whose relative capacity does not meet the standard, the control unit shuts down the corresponding charging module and its liquid cooling supply, and simultaneously shuts down the electromagnetic reversing valve corresponding to the charging module while shutting down the charging module and its liquid cooling supply. After shutting down, the enabling status of the control mode is re-determined.

[0049] In detail, in the above embodiment, the control unit sets corresponding thresholds for the fluctuation accumulation parameter and the fluctuation tendency parameter respectively. For the fluctuation accumulation parameter, it characterizes the capacity stability of the charging module. The upward or downward fluctuation of the charging module relative to the theoretical relative capacity is included in the quantitative statistics of the fluctuation accumulation parameter. The threshold of the fluctuation accumulation parameter can be determined by a limited number of tests on multiple charging modules of the same model. When the capacity stability of the charging module is greater than the threshold, it does not meet the use standard of the charging module. It will not be repeated here.

[0050] The fluctuation tendency parameter represents the capacity change trend of the charging module. Through the cumulative analysis of the change trend of the charging module, the capacity attenuation trend of the battery can be discovered in advance. The threshold of the fluctuation tendency parameter should satisfy the condition that when the fluctuation tendency parameter of the battery is less than the value, the battery capacity is close to being scrapped but has not reached the scrap capacity standard. Of course, it should be understood that since the capacity of the battery is gradually decayed, the threshold of the fluctuation tendency parameter should be a negative value in implementation. In this embodiment, the threshold of the fluctuation tendency parameter is -5% of the relative capacity of the initial cycle of the charging module, which can be set to other values ​​according to actual working conditions and usage requirements.

[0051] Specifically, the process in which the control unit adjusts the opening of the electromagnetic reversing valve based on the difference in the fluctuation accumulation parameter in the second mode includes:

[0052] Determine the opening of the electromagnetic reversing valve between the charging modules based on the fluctuation accumulation parameters of each charging module in a single group;

[0053] The opening degree of the electromagnetic reversing valve is positively correlated with the fluctuation accumulation parameter of the charging module on the outlet side of the electromagnetic reversing valve (ie, the charging module that introduces the coolant through the electromagnetic reversing valve).

[0054] It should be understood that in the first mode, a single charging module only takes in liquid from the liquid inlet and discharges liquid from the liquid outlet, and at the same time, the mutual conduction between the charging modules in the same group increases the coolant flow path. In this embodiment, the control unit sets the electromagnetic reversing valve to unidirectionally conduct toward the charging module with a higher fluctuation accumulation parameter in the second mode, and at the same time adjusts the coolant flow rate to keep the charging module at a preset temperature. The purpose of such a setting is to increase the turbulence of the coolant in the charging module with capacity fluctuation by adding additional coolant flow (stopping the interactive flow in the first mode, but unidirectional targeted coolant flow), thereby improving the liquid cooling effect, ensuring that a better liquid cooling effect can improve the capacity stability of the charging module with capacity fluctuation, and by taking into account the control logic of the remaining charging modules at the same time, if the temperature of the charging module with a slight loss of coolant in a single group of charging modules can be maintained, the liquid cooling effect on the charging module with capacity fluctuation can have a better liquid cooling effect than the first mode, specifically, it can improve the range and uniformity of its internal liquid cooling, thus ensuring the capacity stability of the charging module, thereby improving the capacity stability of the entire liquid-cooled battery pack. In detail, in the second mode, the opening of the electromagnetic reversing valve should not be too large or too small. If it is too large, the Reynolds number of the internal coolant of the charging module that outputs the coolant through the electromagnetic reversing valve will be reduced, thereby causing the temperature control to be unstable. If it is too small, the optimization effect of the charging module measured by the electromagnetic reversing valve for liquid inlet is not obvious, and the capacity fluctuation continues. Therefore, the above-mentioned opening control is set to avoid this phenomenon. This embodiment provides a specific control model for the opening K of the electromagnetic reversing valve.

[0055] ,

[0056] Among them, K0 is the upper limit of the opening of the electromagnetic reversing valve. When the opening of the electromagnetic reversing valve is greater than K0, the temperature of the charging module on the liquid inlet side of the electromagnetic reversing valve cannot be controlled. A1 is the fluctuation cumulative parameter of the charging module on the liquid inlet side of the electromagnetic reversing valve, and A2 is the fluctuation cumulative parameter of the charging module on the liquid outlet side of the electromagnetic reversing valve.

[0057] Specifically, the recording unit stores different liquid cooling degrees and theoretical relative capacities of charging modules at ambient temperatures. The recording unit characterizes the liquid cooling degree through a liquid cooling characteristic value, which is determined by the temperature difference between the liquid outlet pipe and the liquid inlet pipe, and the amount of coolant in the corresponding charging module. The higher the liquid cooling characteristic value, the greater the corresponding liquid cooling degree.

[0058] Among them, the liquid cooling characteristic value is positively correlated with the temperature difference between the liquid inlet pipe and the liquid outlet pipe, and the amount of coolant acting on the charging module (i.e., the volume of coolant flowing through the charging module). This embodiment does not limit the specific method for determining the liquid cooling characteristic value, and it is sufficient to satisfy the above positive correlation. In this way, the corresponding theoretical relative capacity can be determined for different liquid cooling characteristic values ​​and different ambient temperatures through a limited number of tests on standard charging modules and related empirical data.

[0059] Furthermore, the relative capacity of the battery gradually decays with the length of use. In practice, the theoretical relative capacity also changes continuously, but the capacity decay that can be exhibited in a single charge and discharge cycle is relatively small. If it is updated every time or at a regular period, the workload is complicated and difficult to implement. In this embodiment, in order to ensure the timely discovery of the capacity change of the charging module with the length of use, the recording unit outputs the update demand of the theoretical relative capacity of the charging module in response to the fluctuation tendency parameter being a negative value. The characteristic that the fluctuation tendency parameter is accumulated is utilized. When it is a negative value, it indicates that the decay of the relative capacity is more holistic than the single capacity comparison, thereby avoiding blind updating of the theoretical relative capacity.

[0060] In detail, in this embodiment, the capacity of the charging module is determined first, and then the relative capacity of the charging module is determined. The battery capacity C is defined as the amount of charge released during the discharge process, and the determination formula is:

[0061] C=I×t; where C (Ah) is the battery capacity, I (A) is the constant voltage current, and t (h) is the discharge time.

[0062] The determination of the relative capacity Q of the battery is based on the following formula:

[0063] ,

[0064] In the formula, Q is the relative capacity of the battery, Q0 is the initial cycle battery capacity, Q cycle，loss is the attenuation of the battery capacity relative to Q0 in the corresponding cycle.

[0065] In the above embodiment, through the cumulative quantitative analysis of the battery capacity fluctuation, the battery capacity fluctuation can be discovered in time, and the liquid cooling mode is adjusted based on the battery capacity stability to maintain the battery life and usage stability. Through the dual control mode of the first mode and the second mode, the capacity fluctuation state of different charging modules is matched while effectively controlling energy consumption, thereby effectively improving the overall capacity stability of the immersion liquid-cooled battery pack and avoiding the waste of liquid cooling energy caused by uneven distribution of cooling effect due to excessive capacity differences.

[0066] The flowcharts and block diagrams in the accompanying drawings illustrate the possible architecture, functions and operations of the devices, methods and computer program products according to various embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the module, a program segment or a part of the code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based device that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0067] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. An immersion liquid-cooled battery pack, comprising a plurality of liquid-cooled working areas, in which a plurality of groups of two charging modules are arranged in parallel, and a cooling liquid flows through each group of charging modules, characterized in that: The two charging modules of a single group are connected through an electromagnetic reversing valve, and the submerged liquid-cooled battery pack also includes: A collection unit, used to collect the temperature and relative capacity of each charge and discharge cycle of the charging module; The recording unit is configured to obtain, after any charge and discharge cycle, an absolute value of a difference between a relative capacity of each charge and discharge cycle of the charging module and a theoretical relative capacity as a fluctuation value, sum the fluctuation values ​​of each historical charge and discharge cycle as a fluctuation accumulation parameter, and sum the difference between the relative capacity of each historical charge and discharge cycle and the theoretical relative capacity as a fluctuation tendency parameter; The control unit has the following control modes for the liquid cooling working area: In the first mode, the electromagnetic reversing valve is set to a two-way conduction state, and the coolant flow rate is adjusted to keep the charging module at a preset temperature. The enabling condition of the first mode is that the fluctuation cumulative parameters of each charging module in the liquid cooling working area are less than or equal to the corresponding threshold value; In the second mode, the electromagnetic reversing valve is set to be unidirectionally conducted toward the charging module with the high fluctuation accumulation parameter in each group of charging modules, and the coolant flow rate is adjusted to keep the charging module at a preset temperature, and the opening of the electromagnetic reversing valve is adjusted based on the difference in the fluctuation accumulation parameters of each group of charging modules. The enabling condition of the second mode is that there is a charging module with a fluctuation accumulation parameter greater than the corresponding threshold in the liquid cooling working area, and the fluctuation tendency parameters of each charging module in the liquid cooling working area are greater than or equal to the corresponding threshold; Furthermore, the control unit shuts down the corresponding charging module and its liquid cooling supply in response to the existence of a charging module whose fluctuation tendency parameter is less than a corresponding threshold value, or the existence of a charging module whose relative capacity does not meet the standards, and re-determines the enabling status of the control mode after shutdown.

2. The immersion liquid-cooled battery pack according to claim 1, characterized in that: The process of the control unit adjusting the opening of the electromagnetic reversing valve based on the difference of the fluctuation accumulation parameter in the second mode includes: Determine the opening of the electromagnetic reversing valve between the charging modules based on the fluctuation accumulation parameters of each of the single group of charging modules; The opening degree of the electromagnetic reversing valve is positively correlated with the fluctuation accumulation parameter of the charging module on the outlet side of the electromagnetic reversing valve.

3. The immersion liquid-cooled battery pack according to claim 1, characterized in that: The control unit closes the electromagnetic reversing valve corresponding to the charging module while closing the charging module and its liquid cooling supply.

4. The immersion liquid-cooled battery pack according to claim 1, characterized in that: The recording unit stores theoretical relative capacities of the charging module at different liquid cooling levels and ambient temperatures.

5. The immersion liquid-cooled battery pack according to claim 4, characterized in that: In response to the fluctuation tendency parameter being a positive value, the recording unit outputs an update requirement of the theoretical relative capacity of the charging module.

6. The liquid-cooled battery pack according to claim 5, characterized in that: The charging module comprises: A cooling box and a plurality of batteries evenly distributed in the cooling box; A battery bracket, disposed inside the cooling box and used for fixing the battery; A liquid inlet pipe, used for introducing coolant into the cooling box; The liquid outlet pipe is used to discharge the coolant out of the cooling box.

7. The immersion liquid-cooled battery pack according to claim 6, characterized in that: The recording unit characterizes the degree of liquid cooling through a liquid cooling characteristic value, wherein the liquid cooling characteristic value is determined by the temperature difference between the liquid outlet pipe and the liquid inlet pipe, and the amount of coolant in the corresponding charging module, and the higher the value of the liquid cooling characteristic value, the greater the degree of liquid cooling; The liquid cooling characteristic value is positively correlated with the temperature difference between the liquid inlet pipe and the liquid outlet pipe, and the amount of coolant acting on the charging module.

8. The liquid-cooled battery pack according to claim 6, characterized in that: A partition is provided between two charging modules of a single group of charging modules.

9. The liquid-cooled battery pack according to claim 1, characterized in that: Each liquid cooling working area is respectively provided with a coolant inlet and a coolant outlet. The upstream of the coolant inlet is connected to a water pump and a cooling tower in sequence. The coolant inlet is provided with a control valve.

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