A composite dynamic liquid cooling control system and method for power battery packs

Abstract

This invention discloses a composite dynamic liquid cooling control system and method for power battery packs, relating to the field of power battery management technology. It includes: a temperature data acquisition module for collecting surface temperature data of each cell; a calculation module for calculating the extreme temperature difference between cells within the battery module based on the collected temperature data, and simultaneously calculating the average temperature of each battery module; calculating the average temperature range between battery modules based on the average temperature of each battery module; and determining which battery modules require priority cooling based on the extreme temperature difference between cells within the battery module and the average temperature range between battery modules; and a composite liquid cooling control module for adjusting the cooling path according to the determination results to prioritize cooling overheated battery modules. This invention can effectively eliminate localized overheating hotspots, avoiding the risk of internal short circuits or even thermal runaway caused by them; at the same time, it can balance the temperature differences between modules, effectively suppress battery degradation, prevent accelerated battery aging, and extend the service life of the battery pack.

Description

Technical Field

[0001] This invention relates to the field of power battery management technology, and in particular to a composite dynamic liquid cooling control system and method for power battery packs. Background Technology

[0002] The power battery provides energy for the operation of electric vehicles and is a core component of electric vehicles. A power battery typically consists of multiple battery modules, and each battery module is composed of several cells. Currently, lithium-ion batteries are mainly used as individual cells. However, the operating characteristics of lithium-ion batteries are extremely sensitive to temperature changes. Under conditions such as high temperature, high-rate charging, and high-load driving, overheating problems can easily occur, causing the power battery temperature to rise sharply. Since liquid cooling is far more effective than air cooling, current electric vehicle power batteries mainly adopt liquid cooling. The core objective is to remove the heat generated by the battery through the circulation of coolant when the battery temperature is too high, preventing the overall battery temperature from exceeding the safe threshold.

[0003] However, current liquid cooling solutions for power battery packs have a significant limitation: they primarily rely on overall cooling based on overheating temperatures, without prioritizing the cooling of overheated battery modules. If overall cooling is applied directly based on overheating temperatures, the coolant flow rate cannot specifically meet the cooling needs of abnormally overheated cells. If these cells are not adequately cooled, their temperatures will continue to rise, potentially leading to more severe internal short circuits and significantly increasing the risk of thermal runaway. Furthermore, if temperature differences within and between battery modules are not effectively balanced over a long period, the inconsistency within the battery pack will further increase, triggering a chain reaction of accelerated localized aging, shortened overall battery life, and a surge in charging and discharging safety risks.

[0004] Therefore, there is an urgent need to develop a composite dynamic liquid cooling control system and method that can monitor abnormally overheated cells or battery modules in a power battery pack and prioritize their cooling. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems by providing a composite dynamic liquid cooling control system and method for power battery packs. By monitoring abnormally overheated cells or battery modules in the power battery pack and preferentially cooling them, local overheating hotspots can be effectively eliminated, avoiding the risk of internal short circuits or even thermal runaway caused by them. At the same time, it can actively balance the temperature differences between modules, keeping the temperature differences between battery modules within a certain range under overheating conditions during charging and discharging, effectively suppressing battery degradation caused by local overheating, preventing accelerated local battery aging, and extending the overall service life of the battery pack.

[0006] The technical solution adopted in this invention is as follows: a composite dynamic liquid cooling control system for a power battery pack, comprising a temperature data acquisition module, a calculation module, and a composite liquid cooling control module;

[0007] The temperature data acquisition module is used to collect surface temperature data of each cell at different times during charging and discharging.

[0008] The calculation module receives surface temperature data from the temperature data acquisition module, calculates and determines the battery modules in the battery pack that require priority cooling based on the surface temperature data. The calculation module includes a temperature difference extreme value calculation unit, a temperature average value calculation unit, a temperature average value range calculation unit, and a priority cooling module determination unit. The temperature difference extreme value calculation unit calculates the extreme temperature difference between cells within each battery module based on the surface temperature data of each cell acquired by the temperature data acquisition module, and obtains the maximum extreme temperature difference value for each battery module. The temperature average value calculation unit calculates the average temperature of each cell within each battery module based on the surface temperature data of each cell acquired by the temperature data acquisition module. The temperature average value range calculation unit calculates the temperature average value range between battery modules within the battery pack based on the result of the temperature average value calculation unit. The priority cooling module determination unit determines the battery modules in the battery pack that require priority cooling based on the results of the temperature difference extreme value calculation unit and the temperature average value range calculation unit.

[0009] The composite liquid cooling control module includes an inflow main pipe and an outflow main pipe. Multiple parallel battery liquid cooling components are connected between the inflow main pipe and the outflow main pipe. Each battery liquid cooling component includes a battery module and a liquid cooling device. The liquid cooling device is connected to the inflow main pipe via an inflow branch pipe and to the outflow main pipe via an outflow branch pipe. The inflow main pipe is also connected to an auxiliary main pipe via a first three-way valve. The auxiliary main pipe is connected to multiple parallel auxiliary branch pipes, and each auxiliary branch pipe is connected to one of the outflow branch pipes via a second three-way valve. The composite liquid cooling control module also includes a control component. The control component receives the judgment result from the calculation module and sends commands to the first three-way valve and the second three-way valve to control the valve's opening and closing.

[0010] Alternatively, the temperature data acquisition module may be connected to multiple temperature sensors, each of which is connected to a corresponding battery cell.

[0011] Alternatively, the liquid cooling device is a liquid cooling plate, which is disposed on the heat exchange surface of the battery module. The liquid cooling plate has a liquid cooling channel that runs through it. The liquid cooling channel is used to achieve cooling by exchanging heat with the battery module. One end of the liquid cooling channel is connected to the corresponding inflow branch pipe, and the other end is connected to the corresponding outflow branch pipe.

[0012] A composite dynamic liquid cooling control method for a power battery pack, the method being used to control the composite dynamic liquid cooling control system of the power battery pack as described above, comprising the following steps:

[0013] S1. Collect the surface temperature data Ts of each cell at a certain moment;

[0014] S2. Based on the data collected in S1, calculate the extreme temperature difference ΔT between the cells inside each battery module at that moment and the maximum extreme temperature difference of the battery module.

[0015] S3. Calculate the average temperature Tga of each battery module at this moment based on the data collected in S1.

[0016] S4. Calculate the mean temperature range ΔTga between battery modules inside the battery pack using the data obtained from S3.

[0017] S5. Determine which battery module needs to be cooled first based on the extreme temperature difference ΔT between the cells inside the battery module and the average temperature difference ΔTga between the battery modules inside the battery pack.

[0018] S6. Based on the judgment result of S5, control and adjust the valve ports of the first three-way valve and the second three-way valve to achieve priority cooling of a certain battery module.

[0019] Alternatively, S2 may include the following steps:

[0020] S21. Extract the highest temperature value Tma of the cells in each battery module at time nt.

[0021] S22. Extract the lowest temperature value Tmi of the cells in each battery module at time nt;

[0022] S23. Calculate the extreme temperature difference between cells inside each battery module at time nt. The calculation formula is:

[0023]

[0024] Where nt represents a data sampling period of t seconds, with n periods and n=0, 1, 2..., ΔT(m,nt) is the extreme temperature difference between cells of the m-th battery module during the charging and discharging operation at the nt-th second, Tma(m,nt) is the highest surface temperature of the cell in the m-th battery module during the charging and discharging operation at the nt-th second, and Tmi(m,nt) is the lowest surface temperature of the cell in the m-th battery module during the charging and discharging operation at the nt-th second.

[0025] S24. The maximum extreme value of the battery module temperature difference is extracted as follows:

[0026]

[0027] Wherein, ΔT(i,nt) is the extreme temperature difference between the cells of the i-th battery module during the charging and discharging operation at the nt-th second, which is the maximum value among all the extreme temperature differences of the battery modules; ΔT(1,nt) is the extreme temperature difference between the cells of the 1-th battery module during the charging and discharging operation at the nt-th second, and ΔT(2,nt) is the extreme temperature difference between the cells of the 2-th battery module during the charging and discharging operation at the nt-th second.

[0028] Alternatively, the formula for calculating the average temperature Tga of the battery module at time nt in S3 is as follows:

[0029]

[0030] Where nt represents a data sampling period of t seconds, with n periods and n=0, 1, 2, ..., Tga(m,nt) is the average surface temperature of the cells in the m-th battery module during the charging and discharging operation in the nt-th second, Ts(m,1,nt) is the surface temperature value of cell 1 in the m-th battery module during the charging and discharging operation in the nt-th second, Ts(m,2,nt) is the surface temperature value of cell 2 in the m-th battery module during the charging and discharging operation in the nt-th second, Ts(m,Nm,nt) is the surface temperature value of cell Nm in the m-th battery module during the charging and discharging operation in the nt-th second, and Nm is the number of cells in the m-th battery module.

[0031] Alternatively, S4 may include the following steps:

[0032] S41. The maximum average battery module temperature at time nt is:

[0033]

[0034] Where nt represents the data sampling period as t seconds, the number of periods as n and n=0, 1, 2..., Tga(j,nt) is the average temperature between cells of battery module j during charging and discharging at second nt, which is the maximum value among the average temperatures of all battery modules; Tga(1,nt) is the average surface temperature of cell of battery module 1 during charging and discharging at second nt; Tga(2,nt) is the average surface temperature of cell of battery module 2 during charging and discharging at second nt; Tga(m,nt) is the average surface temperature of cell of battery module m during charging and discharging at second nt.

[0035] S42. The minimum average battery module temperature at time nt is:

[0036]

[0037] Where Tga(k,nt) is the average temperature between cells of the k-th battery module during the charging and discharging operation at the nt-th second, and is the minimum value among all battery module temperature averages;

[0038] S43. Calculate the mean temperature range between battery modules within the battery pack at time nt. The calculation formula is as follows:

[0039]

[0040] Wherein, ΔTga(nt) is the mean temperature range of all battery modules inside the battery pack during the charging and discharging operation at the nt second.

[0041] Alternatively, the method for determining the battery module requiring priority cooling at time nt in S5 is as follows:

[0042] Scenario 1: If there is an extreme temperature difference ΔT between cells inside the battery module that is greater than the critical temperature difference β inside the battery module, then the battery module corresponding to the largest extreme temperature difference ΔT(i,nt) will be cooled first, i.e., battery module i.

[0043] Scenario 2: If the extreme temperature difference between cells within all battery modules ΔT ≤ the critical temperature difference β within the battery module, and the average temperature difference between battery modules within the battery pack ΔTga > the critical temperature difference γ between battery modules, then the battery module corresponding to the largest average temperature Tga(j,nt) will be cooled first, i.e., battery module j.

[0044] Scenario 3: If the extreme temperature difference between cells within all battery modules ΔT ≤ the critical temperature difference β within the battery module, and the average temperature difference between battery modules within the battery pack ΔTga ≤ the critical temperature difference γ between battery modules, then there are no battery modules that need to be cooled first.

[0045] Wherein, ΔT(i,nt) is the extreme temperature difference between the cells of the i-th battery module during the charging and discharging operation at the nt-th second, which is the maximum value among all extreme temperature differences of all battery modules; Tga(j,nt) is the average temperature between the cells of the j-th battery module during the charging and discharging operation at the nt-th second, which is the maximum value among all average temperatures of all battery modules.

[0046] Alternatively, in step S6, the method for controlling the valve ports of the first three-way valve and the second three-way valve is as follows:

[0047] When a battery module requires priority cooling, the first three-way valve fully opens the passage between the main inlet pipe and the auxiliary main pipe, and the second three-way valve corresponding to the battery module requiring priority cooling fully opens the passage between the auxiliary branch pipe and the outflow branch pipe; the second three-way valves corresponding to the other battery modules only partially open the passage between the outflow branch pipe and the outflow main pipe, and the opening degree is... ;

[0048] When there are no battery modules requiring priority cooling, the first three-way valve fully opens the passage between the main inflow pipe and the branch inflow pipe; the second three-way valves corresponding to all battery modules only partially open the passage between the branch outflow pipe and the main outflow pipe, with all openings being... Where m is the number of battery modules.

[0049] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0050] The present invention provides a composite dynamic liquid cooling control system and method for power battery packs. By monitoring abnormally overheated cells or battery modules in the power battery pack and preferentially cooling them, it can effectively eliminate local overheating hotspots and avoid the risk of internal short circuits or even thermal runaway caused by them. At the same time, it can actively balance the temperature differences between modules, so that the temperature difference between each battery module is kept within a certain range under the overheating conditions of charging and discharging, effectively suppressing battery degradation caused by local overheating, preventing accelerated local battery aging, and extending the overall service life of the battery pack. Attached Figure Description

[0051] The present invention will be described by way of example and with reference to the accompanying drawings, wherein:

[0052] Figure 1 This is a flowchart of the composite dynamic liquid cooling control method for the power battery pack of the present invention;

[0053] Figure 2 This is a schematic diagram of the hardware for acquiring temperature data during the charging and discharging of the power battery pack.

[0054] Figure 3 This is a schematic diagram of the composite liquid cooling pipeline of the power battery pack;

[0055] Figure 4 This is a schematic diagram of the system hardware composition of the present invention;

[0056] The markings in the diagram are: 1-inflow main pipe; 2-inflow branch pipe; 3-battery liquid cooling assembly; 4-outflow branch pipe; 5-outflow main pipe; 6-auxiliary main pipe; 7-auxiliary branch pipe; 8-first three-way valve; 9-second three-way valve. Detailed Implementation

[0057] The present invention will now be described in detail with reference to the accompanying drawings.

[0058] All features disclosed in this specification, or all steps in all disclosed methods or processes, may be combined in any way, except for mutually exclusive features and / or steps.

[0059] Any feature disclosed in this specification, unless otherwise stated, may be replaced by other equivalent or similar features. That is, unless otherwise stated, each feature is merely one example of a series of equivalent or similar features.

[0060] A composite dynamic liquid cooling control system for power battery packs, such as Figure 1-4 As shown, it includes a temperature data acquisition module, a calculation module, and a composite liquid cooling control module;

[0061] The temperature data acquisition module is used to collect surface temperature data of each cell at different times during charging and discharging.

[0062] The calculation module receives surface temperature data from the temperature data acquisition module, calculates and determines the battery modules in the battery pack that require priority cooling based on the surface temperature data. The calculation module includes a temperature difference extreme value calculation unit, a temperature average value calculation unit, a temperature average value range calculation unit, and a priority cooling module determination unit. The temperature difference extreme value calculation unit calculates the extreme temperature difference between cells within each battery module based on the surface temperature data of each cell acquired by the temperature data acquisition module, and obtains the maximum extreme temperature difference value for each battery module. The temperature average value calculation unit calculates the average temperature of each cell within each battery module based on the surface temperature data of each cell acquired by the temperature data acquisition module. The temperature average value range calculation unit calculates the temperature average value range between battery modules within the battery pack based on the result of the temperature average value calculation unit. The priority cooling module determination unit determines the battery modules in the battery pack that require priority cooling based on the results of the temperature difference extreme value calculation unit and the temperature average value range calculation unit. The various units of the computing module work together to achieve multi-level temperature feature extraction and intelligent decision-making, enabling precise thermal state diagnosis and differentiated cooling control of the power battery system;

[0063] The composite liquid cooling control module includes an inflow main pipe 1 and an outflow main pipe 5. Multiple parallel battery liquid cooling components 3 are connected between the inflow main pipe 1 and the outflow main pipe 5. Each battery liquid cooling component 3 includes a battery module and a liquid cooling device. The liquid cooling device is connected to the inflow main pipe 1 through an inflow branch pipe 2 and to the outflow main pipe 5 through an outflow branch pipe 4. The inflow main pipe 1 is also connected to an auxiliary main pipe 6 through a first three-way valve 8. The auxiliary main pipe 6 is connected to multiple parallel auxiliary branch pipes 7. Each auxiliary branch pipe 7 is connected to one of the outflow branch pipes 4 through a second three-way valve 9. The composite liquid cooling control module also includes a control component, which is used to receive the judgment result of the calculation module and send commands to the first three-way valve 8 and the second three-way valve 9 to control the opening and closing of the valves.

[0064] The main inlet pipe 1 serves as the central distribution point for coolant, delivering coolant to each parallel cooling branch and auxiliary pipe. The main outlet pipe 5 collects and recycles the coolant after heat exchange through the battery modules. The inlet branch pipe 2 connects the main inlet pipe 1 to a single battery module, establishing a directional delivery channel for coolant to a designated battery module. The outlet branch pipe 4 connects the coolant outlet of the battery module to the main outlet pipe 5, exporting the coolant after heat exchange from the battery module to the main outlet pipe 5. The auxiliary main pipe 6 and auxiliary branch pipe 7 form a flow channel independent of each cooling branch, providing a priority cooling channel for battery modules requiring priority cooling. The first three-way valve 8 and the second three-way valve 9 act as dynamic reconfiguration switches for the coolant flow path, enabling instantaneous switching of a series of multiple parallel cooling channels or parallel cooling channels through valve opening and closing combinations. When a battery module requires cooling, the control component controls the valves to open and close, forming a series of parallel cooling channels to prioritize cooling the overheated battery module. When no battery module requires priority cooling, the control component controls the valves to open and close, forming parallel cooling channels to simultaneously cool all battery modules. In summary, based on this composite dynamic liquid cooling pipeline, through the coordinated control of dual three-way valves and auxiliary pipelines, this invention can directly target high-risk modules, simultaneously achieving thermal runaway interception and global temperature equalization.

[0065] Furthermore, the first three-way valve 8 and the second three-way valve 9 are preferably electromagnetic three-way valves. The electromagnetic three-way valve directly drives the valve core by switching the electromagnetic coil on and off, which can convert the digital commands of the control component into physical flow path switching in real time. The electromagnetic three-way valve has the advantages of fast response and precise digital control. The electromagnetic three-way valve is a commonly used device in this field and belongs to the prior art; its specific structure and working principle will not be described in detail in this specification.

[0066] In one alternative implementation, the temperature data acquisition module is connected to multiple temperature sensors, each of which is connected to a corresponding battery cell. The temperature sensors are used to detect the surface temperature data of the battery cell. Further, the temperature sensors can be distributed temperature sensors with multiple temperature probes to detect the real-time temperature values ​​of different battery cells; alternatively, integrated temperature sensor components capable of detecting temperature at different locations can be used. Integrated temperature sensors have simple wiring but lower accuracy; distributed temperature sensors have higher accuracy but more complex wiring.

[0067] In one alternative implementation, the liquid cooling device is a liquid cooling plate disposed on the heat exchange surface of the battery module. The liquid cooling plate has internal liquid cooling channels that penetrate it, and these channels are used to achieve cooling through heat exchange with the battery module. One end of each liquid cooling channel is connected to a corresponding inflow branch pipe 2, and the other end is connected to a corresponding outflow branch pipe 4. The heat generated by the battery module is efficiently conducted to the metal substrate of the liquid cooling plate through a thermally conductive interface material. The coolant flowing through the internal liquid cooling channels of the liquid cooling plate directly contacts the high-temperature metal wall of the liquid cooling plate, thereby carrying away the heat absorbed by the liquid cooling plate and achieving the purpose of cooling the battery module. Using a liquid cooling plate for liquid cooling has the advantages of high heat dissipation efficiency, low space occupancy, strong environmental adaptability, and safety and reliability.

[0068] A composite dynamic liquid cooling control method for a power battery pack, the method being used to control the composite dynamic liquid cooling control system of the power battery pack as described above, comprising the following steps:

[0069] S1. Collect the surface temperature data Ts of each cell at a certain moment;

[0070] S2. Based on the data collected in S1, calculate the extreme temperature difference ΔT between the cells inside each battery module at that moment and the maximum extreme temperature difference of the battery module.

[0071] S3. Calculate the average temperature Tga of each battery module at this moment based on the data collected in S1.

[0072] S4. Calculate the mean temperature range ΔTga between battery modules inside the battery pack using the data obtained from S3.

[0073] S5. Determine which battery module needs to be cooled first based on the extreme temperature difference ΔT between the cells inside the battery module and the average temperature difference ΔTga between the battery modules inside the battery pack.

[0074] S6. Based on the judgment result of S5, control and adjust the valve ports of the first three-way valve 8 and the second three-way valve 9 to achieve priority cooling of a certain battery module.

[0075] The method aims to dynamically identify abnormally overheated cells or modules by calculating the extreme temperature difference ΔT inside the battery module and the average temperature difference ΔTga between modules in real time. It then achieves a composite liquid cooling control target with a series-multiple parallel architecture by adjusting the opening and closing of the first three-way valve 8 and the second three-way valve 9. This allows for the directional distribution of coolant flow, enabling targeted cooling of high-risk areas and balanced and coordinated control of the overall battery temperature. As a result, it suppresses the risk of thermal runaway, optimizes cooling efficiency, and ultimately improves the overall performance, lifespan, and safety of the battery system.

[0076] S1 acquires the surface temperature of each cell in the battery pack at a specific moment in real time, providing the raw data foundation for temperature monitoring and serving as the input source for all subsequent calculations. Its data accuracy directly affects the system's control accuracy. S2 calculates the extreme temperature difference ΔT between cells within the battery module to quantify the temperature uniformity within the module. An excessively large ΔT may trigger localized thermal runaway or lifespan degradation, making it a key indicator for triggering priority cooling. Obtaining the maximum extreme temperature difference between battery modules is used to quickly identify the target module with the highest current thermal runaway risk level. S3 analyzes the temperature distribution of each battery module, reflecting the overall thermal state of the battery module. S4 quantifies the degree of global thermal imbalance in the battery pack. By calculating the difference ΔTga between the maximum and minimum average temperatures of all battery modules, it reveals the overall temperature dispersion between modules, providing a system-level thermal equilibrium criterion for the cooling decision in S5. This, in conjunction with ΔT, determines whether there are high-risk modules requiring priority cooling. S5 is used to dynamically determine cooling priority based on the dual criteria of the extreme temperature difference ΔT within the module and the extreme temperature difference ΔTga between modules: when ΔT exceeds the set threshold β, the battery module corresponding to the largest extreme temperature difference is immediately locked to prevent the risk of thermal runaway; when ΔT does not exceed β but ΔTga exceeds the threshold γ, the battery module corresponding to the largest average temperature is selected for priority cooling; when both parameters are safe, it indicates that the cells in the battery module are in a normal overheating state, the temperature distribution of cells inside and between modules is uniform and the temperature difference is small, and there is no need for priority cooling, only normal cooling needs to be maintained. S6 is used to convert the cooling priority decision of S5 into real-time dynamic control of the three-way valve. By precisely switching the valve opening and closing combination of the three-way valve, the coolant flow path is dynamically changed, so that the cooling flow is directed to the high-risk modules.

[0077] In one alternative implementation, step S2 includes the following steps:

[0078] S21. Extract the highest temperature value Tma of the cells in each battery module at time nt.

[0079] S22. Extract the lowest temperature value Tmi of the cells in each battery module at time nt;

[0080] S23. Calculate the extreme temperature difference between cells inside each battery module at time nt. The calculation formula is:

[0081]

[0082] Where nt represents a data sampling period of t seconds, with n periods and n=0, 1, 2..., ΔT(m,nt) is the extreme temperature difference between cells of the m-th battery module during the charging and discharging operation at the nt-th second, Tma(m,nt) is the highest surface temperature of the cell in the m-th battery module during the charging and discharging operation at the nt-th second, and Tmi(m,nt) is the lowest surface temperature of the cell in the m-th battery module during the charging and discharging operation at the nt-th second.

[0083] S24. The maximum extreme value of the battery module temperature difference is extracted as follows:

[0084]

[0085] Wherein, ΔT(i,nt) is the extreme temperature difference between the cells of the i-th battery module during the charging and discharging operation at the nt-th second, which is the maximum value among all the extreme temperature differences of the battery modules; ΔT(1,nt) is the extreme temperature difference between the cells of the 1-th battery module during the charging and discharging operation at the nt-th second, and ΔT(2,nt) is the extreme temperature difference between the cells of the 2-th battery module during the charging and discharging operation at the nt-th second.

[0086] The highest and lowest temperature values ​​are used to identify temperature anomalies (such as locally overheated cells) within each battery module, providing crucial data for early warning of thermal runaway risks. The extreme temperature difference ΔT is used to quantify the degree of thermal imbalance within the module, serving as the core basis for determining priority cooling strategies in S5. When ΔT exceeds a certain threshold β, it indicates the presence of high-heat-load modules that require priority cooling. The maximum extreme temperature difference of a battery module is used to accurately pinpoint the highest-risk point in the battery pack. When ΔT exceeds a certain threshold β, targeted cooling needs to be performed on the battery module corresponding to the maximum extreme temperature difference of that battery module.

[0087] In one alternative implementation, the formula for calculating the average temperature Tga of the battery module at time nt in S3 is:

[0088]

[0089] Where nt represents a data sampling period of t seconds, with n periods and n=0, 1, 2, ..., Tga(m,nt) is the average surface temperature of the cells in the m-th battery module during the charging and discharging operation in the nt-th second, Ts(m,1,nt) is the surface temperature value of cell 1 in the m-th battery module during the charging and discharging operation in the nt-th second, Ts(m,2,nt) is the surface temperature value of cell 2 in the m-th battery module during the charging and discharging operation in the nt-th second, Ts(m,Nm,nt) is the surface temperature value of cell Nm in the m-th battery module during the charging and discharging operation in the nt-th second, and Nm is the number of cells in the m-th battery module.

[0090] The average temperature Tga of the battery module is the arithmetic mean of the temperatures of all cells in the module. It is used to characterize the average thermal level of the module and provides data support for S4 to calculate the temperature range ΔTga between modules, revealing the system-level thermal distribution imbalance.

[0091] In one alternative implementation, S4 includes the following steps:

[0092] S41. The maximum average battery module temperature at time nt is:

[0093]

[0094] Where nt represents the data sampling period as t seconds, the number of periods as n and n=0, 1, 2..., Tga(j,nt) is the average temperature between cells of battery module j during charging and discharging at second nt, which is the maximum value among the average temperatures of all battery modules; Tga(1,nt) is the average surface temperature of cell of battery module 1 during charging and discharging at second nt; Tga(2,nt) is the average surface temperature of cell of battery module 2 during charging and discharging at second nt; Tga(m,nt) is the average surface temperature of cell of battery module m during charging and discharging at second nt.

[0095] S42. The minimum average battery module temperature at time nt is:

[0096]

[0097] Where Tga(k,nt) is the average temperature between cells of the k-th battery module during the charging and discharging operation at the nt-th second, and is the minimum value among all battery module temperature averages;

[0098] S43. Calculate the mean temperature range between battery modules within the battery pack at time nt. The calculation formula is as follows:

[0099]

[0100] Wherein, ΔTga(nt) is the mean temperature range of all battery modules inside the battery pack during the charging and discharging operation at the nt second.

[0101] The maximum and minimum average battery module temperatures are used to pinpoint system-level thermal risk focal points and identify the module with the highest overall temperature rise in the entire battery pack. The temperature range ΔTga between battery modules within the battery pack is used to quantify the degree of imbalance in the global thermal distribution of the battery pack, providing a system-level thermal balance criterion for S5's cooling decisions. When ΔTga exceeds the threshold γ, it indicates the presence of a high-heat-load module that needs to be prioritized for cooling. This, together with the local temperature difference data from S2, forms a three-level thermal risk prevention and control system of "cell-module-system".

[0102] In one alternative implementation, the method for determining the battery module requiring priority cooling at time nt in S5 is as follows:

[0103] Scenario 1: If there is an extreme temperature difference ΔT between cells inside the battery module that is greater than the critical temperature difference β inside the battery module, then the battery module corresponding to the largest extreme temperature difference ΔT(i,nt) will be cooled first, i.e., battery module i.

[0104] Scenario 2: If the extreme temperature difference between cells within all battery modules ΔT ≤ the critical temperature difference β within the battery module, and the average temperature difference between battery modules within the battery pack ΔTga > the critical temperature difference γ between battery modules, then the battery module corresponding to the largest average temperature Tga(j,nt) will be cooled first, i.e., battery module j.

[0105] Scenario 3: If the extreme temperature difference between cells within all battery modules ΔT ≤ the critical temperature difference β within the battery module, and the average temperature difference between battery modules within the battery pack ΔTga ≤ the critical temperature difference γ between battery modules, then there are no battery modules that need to be cooled first.

[0106] Wherein, ΔT(i,nt) is the extreme temperature difference between the cells of the i-th battery module during the charging and discharging operation at the nt-th second, which is the maximum value among all extreme temperature differences of all battery modules; Tga(j,nt) is the average temperature between the cells of the j-th battery module during the charging and discharging operation at the nt-th second, which is the maximum value among all average temperatures of all battery modules.

[0107] The critical temperature difference β inside the battery module and the critical temperature difference γ between battery modules can be manually set according to the design requirements of battery pack thermal management. Generally, β ≤ 5℃ and γ ≤ 5℃ are selected. The smaller the values ​​of β and γ, the higher the requirement for temperature consistency control inside the battery pack. At the same time, the values ​​of β and γ cannot be large, otherwise the larger the temperature difference, the worse the consistency, and the shorter the service life.

[0108] The dual criteria of the extreme internal temperature difference ΔT and the extreme temperature difference between modules ΔTga are introduced to determine whether there are abnormally overheated cells within the battery module. If ΔT > β, there are abnormally overheated cells within the module, indicating a high-risk module. If these cells are not adequately cooled, their temperature will continue to rise, potentially accelerating aging, causing more severe internal short circuits, and ultimately greatly increasing the risk of thermal runaway. Therefore, in this case, the battery module corresponding to the largest extreme temperature difference ΔT(i,nt) needs to be prioritized for cooling to prevent a chain reaction caused by localized overheating. If ΔT ≤ β, but ΔTga > γ, there is systematic temperature stratification between modules, indicating potentially risky modules. If these modules are not balanced over a long period, the inconsistency of the battery pack may further increase, leading to a chain reaction of accelerated localized aging, shortened overall battery life, and a surge in charging and discharging safety risks. Therefore, in this case, the battery module corresponding to the largest average battery temperature Tga(j,nt) needs to be prioritized for cooling to suppress the increase in battery pack inconsistency. In principle, as long as ΔT≤β and ΔTga≤γ, it indicates that all cells within the module are under normal overheating, and the overheating temperatures are basically consistent. In this case, there are no abnormally overheated cells within the battery module, and indiscriminate cooling of all battery modules is sufficient. This allows the system to operate in a more balanced and energy-efficient manner, eliminating the need for excessive cooling of individual points and thus optimizing system efficiency. Furthermore, in executing the above three scenarios, cooling is prioritized for scenario one, followed by scenario two, and finally scenario three. In summary, the above discrimination method classifies thermal risk into three levels—high risk, potential risk, and safe state—using dual thresholds of β and γ. The constructed three-level dynamic decision-making mechanism for thermal risk enables precise targeted allocation of cooling resources, effectively avoiding the risk of internal short circuits or even thermal runaway caused by localized overheating, preventing accelerated localized battery aging, and extending the overall lifespan of the battery pack.

[0109] In one alternative implementation, in step S6, the method for controlling the valve ports of the first three-way valve 8 and the second three-way valve 9 is as follows:

[0110] When a battery module requires priority cooling, the first three-way valve 8 fully opens the passage between the inflow main pipe 1 and the auxiliary main pipe 6, allowing 100% of the coolant to flow into the auxiliary main pipe 6. The second three-way valve 9 corresponding to the battery module requiring priority cooling fully opens the passage between the auxiliary branch pipe 7 and the outflow branch pipe 4, allowing all the coolant to flow to the high-risk module for full-force cooling. The second three-way valves 9 corresponding to the remaining battery modules only partially open the passage between the outflow branch pipe 4 and the outflow main pipe 5, with all openings being... At this point, a series of parallel liquid cooling paths are formed. The second three-way valve 9 corresponding to the other battery modules is partially open to ensure that the flow rate through the other liquid cooling plates is equal. If the other second three-way valves 9 are fully open, the flow rate through the other liquid cooling plates may be unequal.

[0111] When there are no battery modules requiring priority cooling, the first three-way valve 8 fully opens the passage between the main inflow pipe 1 and the branch inflow pipe 2; the second three-way valves 9 corresponding to all battery modules only partially open the passage between the branch outflow pipe 4 and the main outflow pipe 5, with all valves having an opening degree of [missing information]. The coolant is evenly distributed to each parallel branch; where m is the number of battery modules.

[0112] Example

[0113] Taking a battery pack composed of 48 square lithium-ion cells as an example, the battery pack contains 6 battery modules, each of which consists of 8 cells connected in series. Under an ambient temperature of 30℃, it is charged at a 3C rate. By collecting the cell operating temperature data at a certain moment during the charging process, the method and process of this technology are specifically analyzed and introduced.

[0114] S1. Collect the operating temperature data of each battery cell;

[0115] The surface temperature data of each cell at a certain moment (denoted as nt moment) during the charging process were collected, as shown in Table 1 below:

[0116] Table 1

[0117]

[0118] S2. Calculate the maximum temperature difference for each battery module;

[0119] The highest and lowest cell temperatures and extreme temperature differences between cells for each battery module during the charging and discharging operation at the nt second are calculated, as shown in Table 2 below:

[0120] Table 2

[0121]

[0122] Therefore, the maximum temperature difference extreme value of the battery module can be extracted from Table 2 as 3.2℃, which is the maximum temperature difference extreme value between the cells of battery module No. 4 when it is charging and discharging at the nt second. It is the maximum value among all battery module temperature difference extreme values.

[0123] S3. Calculate the average temperature of each battery module;

[0124] The average cell surface temperature of each battery module during the charging and discharging operation at the nt second is calculated, as shown in Table 3 below:

[0125] Table 3

[0126]

[0127] S4. Calculate the mean temperature range of the battery module;

[0128] From Table 3 above, the highest average battery module temperature is 45℃, which is the average temperature between cells of battery module 4 during the charging and discharging operation at the nt second. The lowest average battery module temperature is 40.6℃, which is the average temperature between cells of battery module 1 during the charging and discharging operation at the nt second. Therefore, the range of average temperatures for all battery modules during the charging and discharging operation at the nt second can be calculated as ΔTga(nt) = 45℃ - 40.6℃ = 4.4℃.

[0129] S5. Determine which battery module should be prioritized for cooling;

[0130] The critical temperature difference β inside the battery module is set to 3℃, and the critical temperature difference γ between battery modules is set to 1℃. Since the extreme temperature difference ΔT(4,nt) = 3.2℃ of the cells inside the battery module is greater than the critical temperature difference β inside the battery module, battery module No. 4 is selected for priority cooling.

[0131] S6, Dynamically controlled composite liquid cooling path;

[0132] Since there are battery modules that require priority cooling, the specific control relationship of the composite liquid cooling path of the power battery pack during the charging and discharging operation in the (n+1)th cycle is as follows: the AC end of the first three-way valve 8 is fully open, and the AB end is closed; the ac end of the second three-way valve 9 of battery module 4 is fully open, and the ab end is closed, so that battery module 4 can be cooled preferentially and quickly; the ab end of the second three-way valve 9 of battery modules 1, 2, 3, 5, and 6 is partially open (opening degree is 20%), and the ac end is closed, so that battery modules 1, 2, 3, 5, and 6 are cooled in parallel with the same coolant flow rate.

[0133] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0134] The present invention provides a composite dynamic liquid cooling control system and method for power battery packs. By monitoring abnormally overheated cells or battery modules in the power battery pack and preferentially cooling them, it can effectively eliminate local overheating hotspots and avoid the risk of internal short circuits or even thermal runaway caused by them. At the same time, it can actively balance the temperature differences between modules, so that the temperature difference between each battery module is kept within a certain range under the overheating conditions of charging and discharging, effectively suppressing battery degradation caused by local overheating, preventing accelerated local battery aging, and extending the overall service life of the battery pack.

[0135] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A composite dynamic liquid cooling control system for a power battery pack, characterized in that: It includes a temperature data acquisition module, a calculation module, and a composite liquid cooling control module; The temperature data acquisition module is used to collect surface temperature data of each cell at different times during charging and discharging. The calculation module receives surface temperature data from the temperature data acquisition module, calculates and determines the battery modules in the battery pack that require priority cooling based on the surface temperature data. The calculation module includes a temperature difference extreme value calculation unit, a temperature average value calculation unit, a temperature average value range calculation unit, and a priority cooling module determination unit. The temperature difference extreme value calculation unit calculates the extreme temperature difference between cells within each battery module based on the surface temperature data of each cell acquired by the temperature data acquisition module, and obtains the maximum extreme temperature difference value for each battery module. The temperature average value calculation unit calculates the average temperature of each cell within each battery module based on the surface temperature data of each cell acquired by the temperature data acquisition module. The temperature average value range calculation unit calculates the temperature average value range between battery modules within the battery pack based on the result of the temperature average value calculation unit. The priority cooling module determination unit determines the battery modules in the battery pack that require priority cooling based on the results of the temperature difference extreme value calculation unit and the temperature average value range calculation unit. The composite liquid cooling control module includes an inflow main pipe (1) and an outflow main pipe (5). Multiple parallel battery liquid cooling components (3) are connected between the inflow main pipe (1) and the outflow main pipe (5). Each battery liquid cooling component (3) includes a battery module and a liquid cooling device. The liquid cooling device is connected to the inflow main pipe (1) through an inflow branch pipe (2) and to the outflow main pipe (5) through an outflow branch pipe (4). The inflow main pipe (1) is also connected to an auxiliary main pipe (6) through a first three-way valve (8). The auxiliary main pipe (6) is connected to multiple parallel auxiliary branch pipes (7). Each auxiliary branch pipe (7) is connected to an outflow branch pipe (4) through a second three-way valve (9). The composite liquid cooling control module also includes a control component. The control component is used to receive the judgment result of the calculation module and send instructions to the first three-way valve (8) and the second three-way valve (9) to control the opening and closing of the valves.

2. The composite dynamic liquid cooling control system for the power battery pack as described in claim 1, characterized in that: The temperature data acquisition module is connected to multiple temperature sensors, and each temperature sensor is connected to a corresponding battery cell.

3. The composite dynamic liquid cooling control system for the power battery pack as described in claim 1, characterized in that: The liquid cooling device is a liquid cooling plate, which is disposed on the heat exchange surface of the battery module. The liquid cooling plate has a liquid cooling channel that runs through it. The liquid cooling channel is used to achieve cooling by exchanging heat with the battery module. One end of the liquid cooling channel is connected to the corresponding inflow branch pipe (2), and the other end is connected to the corresponding outflow branch pipe (4).

4. A composite dynamic liquid cooling control method for a power battery pack, characterized in that: The method is used to control the composite dynamic liquid cooling control system of the power battery pack as described in any one of claims 1-3, and includes the following steps: S1. Collect the surface temperature data Ts of each cell at a certain moment; S2. Based on the data collected in S1, calculate the extreme temperature difference ΔT between the cells inside each battery module at that moment and the maximum extreme temperature difference of the battery module. S3. Calculate the average temperature Tga of each battery module at this moment based on the data collected in S1. S4. Calculate the mean temperature range ΔTga between battery modules inside the battery pack using the data obtained from S3. S5. Determine which battery module needs to be cooled first based on the extreme temperature difference ΔT between the cells inside the battery module and the average temperature difference ΔTga between the battery modules inside the battery pack. S6. Based on the judgment result of S5, control and adjust the valve ports of the first three-way valve (8) and the second three-way valve (9) to achieve priority cooling of a certain battery module.

5. The composite dynamic liquid cooling control method for power battery packs as described in claim 4, characterized in that: S2 includes the following steps: S21. Extract the highest temperature value Tma of the cells in each battery module at time nt. S22. Extract the lowest temperature value Tmi of the cells in each battery module at time nt; S23. Calculate the extreme temperature difference between cells inside each battery module at time nt. The calculation formula is: Where nt represents a data sampling period of t seconds, with n periods and n=0, 1, 2..., ΔT(m,nt) is the extreme temperature difference between cells of the m-th battery module during the charging and discharging operation at the nt-th second, Tma(m,nt) is the highest surface temperature of the cell in the m-th battery module during the charging and discharging operation at the nt-th second, and Tmi(m,nt) is the lowest surface temperature of the cell in the m-th battery module during the charging and discharging operation at the nt-th second. S24. The maximum extreme value of the battery module temperature difference is extracted as follows: Wherein, ΔT(i,nt) is the extreme temperature difference between the cells of the i-th battery module during the charging and discharging operation at the nt-th second, which is the maximum value among all the extreme temperature differences of the battery modules; ΔT(1,nt) is the extreme temperature difference between the cells of the 1-th battery module during the charging and discharging operation at the nt-th second, and ΔT(2,nt) is the extreme temperature difference between the cells of the 2-th battery module during the charging and discharging operation at the nt-th second.

6. The composite dynamic liquid cooling control method for power battery packs as described in claim 4, characterized in that: The formula for calculating the average temperature Tga of the battery module at time nt in S3 is as follows: Where nt represents a data sampling period of t seconds, with n periods and n=0, 1, 2, ..., Tga(m,nt) is the average surface temperature of the cells in the m-th battery module during the charging and discharging operation in the nt-th second, Ts(m,1,nt) is the surface temperature value of cell 1 in the m-th battery module during the charging and discharging operation in the nt-th second, Ts(m,2,nt) is the surface temperature value of cell 2 in the m-th battery module during the charging and discharging operation in the nt-th second, Ts(m,Nm,nt) is the surface temperature value of cell Nm in the m-th battery module during the charging and discharging operation in the nt-th second, and Nm is the number of cells in the m-th battery module.

7. The composite dynamic liquid cooling control method for power battery packs as described in claim 4, characterized in that: S4 includes the following steps: S41. The maximum average battery module temperature at time nt is: Where nt represents the data sampling period as t seconds, the number of periods as n and n=0, 1, 2..., Tga(j,nt) is the average temperature between cells of battery module j during charging and discharging at second nt, which is the maximum value among the average temperatures of all battery modules; Tga(1,nt) is the average surface temperature of cell of battery module 1 during charging and discharging at second nt; Tga(2,nt) is the average surface temperature of cell of battery module 2 during charging and discharging at second nt; Tga(m,nt) is the average surface temperature of cell of battery module m during charging and discharging at second nt. S42. The minimum average battery module temperature at time nt is: Where Tga(k,nt) is the average temperature between cells of the k-th battery module during the charging and discharging operation at the nt-th second, and is the minimum value among all battery module temperature averages; S43. Calculate the mean temperature range between battery modules within the battery pack at time nt. The calculation formula is as follows: Wherein, ΔTga(nt) is the mean temperature range of all battery modules inside the battery pack during the charging and discharging operation at the nt second.

8. The composite dynamic liquid cooling control method for power battery packs as described in claim 4, characterized in that: The method for determining the battery module that needs priority cooling at time nt in S5 is as follows: Scenario 1: If there is an extreme temperature difference ΔT between cells inside the battery module that is greater than the critical temperature difference β inside the battery module, then the battery module corresponding to the largest extreme temperature difference ΔT(i,nt) will be cooled first, i.e., battery module i. Scenario 2: If the extreme temperature difference between cells within all battery modules ΔT ≤ the critical temperature difference β within the battery module, and the average temperature difference between battery modules within the battery pack ΔTga > the critical temperature difference γ between battery modules, then the battery module corresponding to the largest average temperature Tga(j,nt) will be cooled first, i.e., battery module j. Scenario 3: If the extreme temperature difference between cells within all battery modules ΔT ≤ the critical temperature difference β within the battery module, and the average temperature difference between battery modules within the battery pack ΔTga ≤ the critical temperature difference γ between battery modules, then there are no battery modules that need to be cooled first. Wherein, ΔT(i,nt) is the extreme temperature difference between the cells of the i-th battery module during the charging and discharging operation at the nt-th second, which is the maximum value among all extreme temperature differences of all battery modules; Tga(j,nt) is the average temperature between the cells of the j-th battery module during the charging and discharging operation at the nt-th second, which is the maximum value among all average temperatures of all battery modules.

9. The composite dynamic liquid cooling control method for power battery packs as described in claim 4, characterized in that: In step S6, the method for controlling and adjusting the valve ports of the first three-way valve (8) and the second three-way valve (9) is as follows: When a battery module requires priority cooling, the first three-way valve (8) fully opens the passage between the inflow main pipe (1) and the auxiliary main pipe (6), and the second three-way valve (9) corresponding to the battery module requiring priority cooling fully opens the passage between the auxiliary branch pipe (7) and the outflow branch pipe (4); the second three-way valves (9) corresponding to the other battery modules only partially open the passage between the outflow branch pipe (4) and the outflow main pipe (5), and the opening degree is... ; When there are no battery modules that require priority cooling, the first three-way valve (8) fully opens the passage between the inflow main pipe (1) and the inflow branch pipe (2); the second three-way valves (9) corresponding to all battery modules only partially open the passage between the outflow branch pipe (4) and the outflow main pipe (5), and the opening degree is... Where m is the number of battery modules.

Images