Combined type dynamic liquid cooling control system and method for power battery pack

Abstract

The invention discloses a composite dynamic liquid cooling control system and method for a power battery pack, and relates to the technical field of power battery management, and the system comprises a temperature data collection module which is used for collecting the surface temperature data of each battery cell; the calculation module is used for calculating a temperature difference extreme value between battery cells in the battery modules based on the collected temperature data, calculating a temperature mean value of each battery module, and calculating a temperature mean value range between the battery modules based on the temperature mean value of each battery module; according to the temperature difference extreme value between the battery cells in the battery modules and the temperature mean value range between the battery modules, the battery modules needing to be cooled preferentially are judged; the composite liquid cooling control module adjusts the cooling path according to the judgment result so as to preferentially cool the overheated battery module. Local over-temperature hot spots can be effectively eliminated, and internal short circuit and even thermal runaway risks caused by the local over-temperature hot spots are avoided; meanwhile, the temperature difference between the modules can be balanced, battery attenuation is effectively inhibited, battery aging is prevented from being accelerated, and the service life of the battery pack is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of power battery management, and in particular to a composite dynamic liquid cooling control system and method for a power battery pack. Background Art

[0002] Power batteries provide the energy needed for electric vehicles and are their core component. Power batteries typically consist of multiple battery modules, each of which is composed of several cells. Currently, lithium-ion batteries are primarily used as single cells. However, their operating characteristics are extremely sensitive to temperature changes, making them prone to overheating in high-temperature environments, during high-rate charging, and under high-load conditions, causing the power battery temperature to rise sharply. Liquid cooling is currently the primary method for dissipating heat in electric vehicle power batteries, as it is far superior to air cooling. Its core goal is to remove heat generated by the battery through the circulation of coolant when the battery temperature is too high, preventing the overall battery temperature from exceeding a safe threshold.

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

[0004] To this end, 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 cool them preferentially. Summary of the Invention

[0005] The purpose of the present invention is to provide a composite dynamic liquid cooling control system and method for a power battery pack in response to the above-mentioned problems. By monitoring abnormally overheated cells or battery modules in the power battery pack and cooling them preferentially, local overheating hot spots can be effectively eliminated to avoid the risk of internal short circuits or even thermal runaway caused by them. At the same time, the temperature differences between modules can be actively balanced to keep the temperature differences of each battery module within a certain range under the overheating conditions of charging and discharging, effectively suppressing battery attenuation caused by local overheating, preventing accelerated local battery aging, and extending the overall service life of the battery pack.

[0006] The technical solution adopted by the present 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; The temperature data acquisition module is used to collect surface temperature data of each battery cell at different times during charging and discharging operation; The calculation module is used to receive the surface temperature data from the temperature data acquisition module, and calculate and determine the battery module in the battery pack that needs to be cooled first based on the surface temperature data; The composite liquid cooling control module includes an inflow main pipe and an outflow main pipe, and multiple parallel battery liquid cooling components are connected between the inflow main pipe and the outflow main pipe. The battery liquid cooling component includes a battery module and a liquid cooling device. The liquid cooling device is connected to the inflow main pipe through an inflow branch pipe, and the liquid cooling device is connected to the outflow main pipe through an outflow branch pipe. The inflow main pipe is also connected to an auxiliary main pipe through a first three-way valve. The auxiliary main pipe is connected to multiple parallel auxiliary branches, and each of the auxiliary branches is connected to one of the outflow branches through a second three-way valve. The composite liquid cooling control module also includes a control component, which is used to receive the determination result of the calculation module and send instructions to the first three-way valve and the second three-way valve to control the opening and closing of the valves.

[0007] Optionally, the temperature data acquisition module is connected to a plurality of temperature sensors, and each of the temperature sensors is correspondingly connected to a battery cell.

[0008] Optionally, the calculation module includes a temperature difference extreme value calculation unit, a temperature mean calculation unit, a temperature mean extreme value calculation unit, and a priority cooling module determination unit; the temperature difference extreme value calculation unit is used to calculate the temperature difference extreme value between the battery cells inside each battery module based on the surface temperature data of each battery cell collected by the temperature data acquisition module, and obtain the maximum battery module temperature difference extreme value; the temperature mean calculation unit is used to calculate the temperature mean of the battery cells inside each battery module based on the surface temperature data of each battery cell collected by the temperature data acquisition module; the temperature mean extreme value calculation unit is used to calculate the temperature mean extreme value between the battery modules inside the battery pack based on the result of the temperature mean calculation unit; the priority cooling module determination unit is used to determine the battery module in the battery pack that needs priority cooling based on the results of the temperature difference extreme value calculation unit and the temperature mean extreme value calculation unit.

[0009] Optionally, the liquid cooling device is a liquid cooling plate, which is arranged on the heat exchange surface of the battery module. A liquid cooling channel is provided inside the liquid cooling plate and passes through the liquid cooling plate. The liquid cooling channel is used to achieve cooling by heat exchange with the battery module; one end of the liquid cooling channel is connected to the corresponding inlet branch, and the other end is connected to the corresponding outflow branch.

[0010] 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: S1, collecting the surface temperature data Ts of each battery cell at a certain moment; S2. Calculate the temperature difference extreme value ΔT between the battery cells in each battery module at that moment and the maximum battery module temperature difference extreme value based on the data collected in S1; S3. Calculate the average temperature Tga of each battery module at that moment based on the data collected in S1; S4. Calculate the temperature range difference ΔTga between battery modules in the battery pack using the data calculated in S3; S5. Determine the battery module that needs to be cooled first based on the temperature difference extreme value ΔT between the battery cells in the battery module and the temperature mean extreme value ΔTga between the battery modules in the battery pack; S6. Based on the determination result of S5, control and adjust the valve openings of the first three-way valve and the second three-way valve to achieve preferential cooling of a certain battery module.

[0011] Optionally, S2 includes the following steps: S21, extracting the maximum temperature value Tma of the battery cells in each battery module at time nt; S22, extracting the lowest temperature value Tmi of the battery cells in each battery module at time nt; S23. Calculate the temperature difference between the cells in each battery module at time nt using the following formula:

[0012] Wherein, nt represents the data sampling period of t seconds, the number of periods is n and n=0, 1, 2, etc., ΔT(m,nt) is the extreme temperature difference between the cells of the m-th battery module during the charge and discharge operation at the nt-th second, Tma(m,nt) is the maximum surface temperature of the cells in the m-th battery module during the charge and discharge operation at the nt-th second, and Tmi(m,nt) is the minimum surface temperature of the cells in the m-th battery module during the charge and discharge operation at the nt-th second; S24. Extract the maximum battery module temperature difference extreme value:

[0013] Among them, ΔT(i,nt) is the extreme temperature difference between the cells of the i-th battery module during charging and discharging at the nt-th second, which is the maximum temperature difference among all battery modules; ΔT(1,nt) is the extreme temperature difference between the cells of the No. 1 battery module during charging and discharging at the nt-th second, and ΔT(2,nt) is the extreme temperature difference between the cells of the No. 2 battery module during charging and discharging at the nt-th second.

[0014] Alternatively, the calculation formula for the average temperature Tga of the battery module at time nt in S3 is:

[0015] Wherein, nt indicates that the data sampling period is t seconds, the number of periods is n and n=0, 1, 2, etc., Tga(m,nt) is the average surface temperature of the battery cells of the m-th battery module during charging and discharging at the nt-th second, Ts(m,1,nt) is the surface temperature value of the No. 1 battery cell of the m-th battery module collected during charging and discharging at the nt-th second, Ts(m,2,nt) is the surface temperature value of the No. 2 battery cell of the m-th battery module collected during charging and discharging at the nt-th second, Ts(m,Nm,nt) is the surface temperature value of the No. Nm battery cell of the m-th battery module collected during charging and discharging at the nt-th second, and Nm is the number of battery cells contained in the m-th battery module.

[0016] Optionally, the S4 includes the following steps: S41. Extract the maximum average battery module temperature at time nt:

[0017] Wherein, nt represents the data sampling period of t seconds, the number of periods is n and n=0, 1, 2, etc., Tga(j,nt) is the average temperature between the cells of the j-th battery module during the charge and discharge operation at the nt-th second, which is the maximum value among the average temperatures of all battery modules; Tga(1,nt) is the average surface temperature of the cells of the 1-th battery module during the charge and discharge operation at the nt-th second; Tga(2,nt) is the average surface temperature of the cells of the 2-th battery module during the charge and discharge operation at the nt-th second; Tga(m,nt) is the average surface temperature of the cells of the m-th battery module during the charge and discharge operation at the nt-th second; S42. Extract the minimum average battery module temperature at time nt:

[0018] Wherein, Tga(k,nt) is the average temperature between the cells of the k-th battery module during the charge and discharge operation at the nt-th second, and is the minimum value among the average temperatures of all battery modules; S43. Calculate the temperature range between the battery modules in the battery pack at time nt using the following formula:

[0019] Among them, ΔTga(nt) is the average temperature difference of all battery modules inside the battery pack during charging and discharging at the ntth second.

[0020] Alternatively, the method for determining the battery module that needs to be cooled first at time nt in S5 is: Case 1: If the temperature difference between the cells inside the battery module is greater than the critical temperature difference β inside the battery module, the battery module corresponding to the largest temperature difference between the cells ΔT(i,nt) is cooled first, i.e., battery module number i. Case 2: If the temperature difference between the cells inside all battery modules ΔT≤ the temperature difference threshold β, and the temperature difference between the battery modules inside the battery pack ΔTga> the temperature difference threshold γ, then the battery module corresponding to the largest average battery module temperature Tga(j,nt), that is, battery module number j, is cooled first. Case 3: If the temperature difference between the cells in all battery modules ΔT≤ the temperature difference threshold β within the battery module, and the average temperature difference between the battery modules in the battery pack ΔTga≤ the temperature difference threshold γ between the battery modules, then there is no battery module that requires priority cooling; Wherein, ΔT(i,nt) is the extreme temperature difference between the cells of the i-th battery module during charging and discharging at the nt-th second, which is the maximum value among the extreme temperature differences of all battery modules; Tga(j,nt) is the average temperature between the cells of the j-th battery module during charging and discharging at the nt-th second, which is the maximum value among the average temperatures of all battery modules.

[0021] Alternatively, in S6, the method for controlling and adjusting the valve ports of the first three-way valve and the second three-way valve is: When there is a battery module that needs priority cooling, the first three-way valve only fully opens the passage between the inlet main pipe and the auxiliary main pipe, and the second three-way valve corresponding to the battery module that needs priority cooling only fully opens the passage between the auxiliary branch pipe and the outflow branch pipe; the second three-way valves corresponding to the remaining battery modules only partially open the passage between the outflow branch pipe and the outflow main pipe, and the opening degree is ; When there is no battery module that needs priority cooling, the first three-way valve only fully opens the passage between the inflow main pipe and the inflow branch pipe; the second three-way valves corresponding to all battery modules only partially open the passage between the outflow branch pipe and the outflow main pipe, and the opening degree is ; Where m is the number of battery modules.

[0022] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: The present invention provides a composite dynamic liquid cooling control system and method for a power battery pack. By monitoring abnormally overheated cells or battery modules in the power battery pack and cooling them preferentially, it can effectively eliminate local overheating hot spots 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 differences between each battery module of the battery pack are kept 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 This is a flow chart of the composite dynamic liquid cooling control method for a power battery pack of the present invention; Figure 2 This is a schematic diagram of the hardware for collecting temperature data during the charging and discharging of the power battery pack; Figure 3 This is a hardware diagram of the composite liquid cooling pipeline for the power battery pack; Figure 4 It is a schematic diagram of the system hardware composition of the present invention; Markings in the figure: 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 DESCRIPTION

[0024] The present invention will be described in detail below with reference to the accompanying drawings.

[0025] All features disclosed in this specification, or all steps in the disclosed methods or processes, except mutually exclusive features and / or steps, can be combined in any manner.

[0026] 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 only an example of a series of equivalent or similar features.

[0027] A composite dynamic liquid cooling control system for a power battery pack, such as Figure 1-4 As shown, 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 battery cell at different times during charging and discharging operation; The calculation module is used to receive the surface temperature data from the temperature data acquisition module, and calculate and determine the battery module in the battery pack that needs to be cooled first based on the surface temperature data; The composite liquid cooling control module includes an inflow main pipe 1 and an outflow main pipe 5, and multiple parallel battery liquid cooling components 3 are connected between the inflow main pipe 1 and the outflow main pipe 5. The 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 the liquid cooling device is connected 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, and each of the auxiliary branch pipes 7 is connected to one of the outflow branches 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 determination 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.

[0028] Among them, the inflow main pipe 1 serves as the coolant distribution center, transporting the coolant to each parallel cooling branch and auxiliary pipe; the outflow main pipe 5 collects the coolant after heat exchange through the battery module and recycles it; the inflow branch pipe 2 connects the inflow main pipe 1 with a single battery module to establish a directional delivery channel for the coolant to the designated battery module; the outflow branch pipe 4 connects the battery module coolant outlet with the outflow main pipe 5, and guides the coolant that has completed the heat exchange from the battery module to the outflow main pipe 5. The auxiliary main pipe 6 and the auxiliary branch pipe 7 constitute a flow channel independent of each cooling branch, providing a priority cooling channel for the battery module that needs priority cooling. The first three-way valve 8 and the second three-way valve 9 serve as dynamic reconstruction switches for the coolant flow channel. Through the combination of valve opening and closing, instantaneous switching of a series of multiple parallel cooling channels or parallel cooling channels can be achieved. When there are battery modules that need cooling, the control component controls the valves to open and close to form a series of multiple parallel cooling channels, giving priority to cooling the overheated battery modules; when there are no battery modules that need cooling, the control component controls the valves to open and close to form parallel cooling channels, cooling all battery modules simultaneously. In summary, based on this composite dynamic liquid cooling circuit, through the coordinated control of the dual three-way valves and auxiliary pipelines, the present invention can directly target high-risk modules and simultaneously achieve thermal runaway interception and global temperature balance.

[0029] Furthermore, the first three-way valve 8 and the second three-way valve 9 are preferably electromagnetic three-way valves. Electromagnetic three-way valves directly drive the valve core by turning the electromagnetic coil on and off, converting digital instructions from the control component into physical flow path switching in real time. Electromagnetic three-way valves have the advantages of fast response and digital precision control. Electromagnetic three-way valves are commonly used in the field and belong to the prior art. Their specific structure and operating principle will not be further described in this specification.

[0030] In one alternative embodiment, 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 cells. Furthermore, 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 assemblies capable of detecting temperature at different locations can be used. Integrated temperature sensors have simple wiring but lower accuracy, while distributed temperature sensors have higher accuracy but more complex wiring.

[0031] In an alternative embodiment, the calculation module includes a temperature difference extreme value calculation unit, a temperature mean calculation unit, a temperature mean extreme difference calculation unit, and a priority cooling module determination unit. The temperature difference extreme value calculation unit is used to calculate the temperature difference extreme value between the cells within each battery module based on the surface temperature data of each cell collected by the temperature data acquisition module, and obtain the maximum battery module temperature difference extreme value. The temperature mean calculation unit is used to calculate the temperature mean of the cells within each battery module based on the surface temperature data of each cell collected by the temperature data acquisition module. The temperature mean extreme difference calculation unit is used to calculate the temperature mean extreme difference between the battery modules within the battery pack based on the results of the temperature mean calculation unit. The priority cooling module determination unit is used to determine the battery module in the battery pack that requires priority cooling based on the results of the temperature difference extreme value calculation unit and the temperature mean extreme difference calculation unit. The various units of the calculation module work together to realize multi-level temperature feature extraction and intelligent decision-making, realizing accurate thermal state diagnosis and differentiated cooling control of the power battery system.

[0032] In an alternative embodiment, the liquid cooling device is a liquid cooling plate, which is arranged on the heat exchange surface of the battery module. A liquid cooling channel is provided inside the liquid cooling plate and passes through the liquid cooling plate. 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 inlet branch 2, and the other end is connected to the corresponding outlet branch 4. The heat generated by the battery module is efficiently transferred to the metal substrate of the liquid cooling plate through the thermal interface material, and the coolant flowing through the liquid cooling channel inside the liquid cooling plate is in direct contact with the high-temperature metal wall of the liquid cooling plate, thereby taking away the heat absorbed by the liquid cooling plate and achieving the purpose of cooling the battery module. The use of 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.

[0033] 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: S1, collecting the surface temperature data Ts of each battery cell at a certain moment; S2. Calculate the temperature difference extreme value ΔT between the battery cells in each battery module at that moment and the maximum battery module temperature difference extreme value based on the data collected in S1; S3. Calculate the average temperature Tga of each battery module at that moment based on the data collected in S1; S4. Calculate the temperature range difference ΔTga between battery modules in the battery pack using the data calculated in S3; S5. Determine the battery module that needs to be cooled first based on the temperature difference extreme value ΔT between the battery cells in the battery module and the temperature mean extreme value ΔTga between the battery modules in the battery pack; S6. Based on the determination result of S5, control and adjust the valve openings of the first three-way valve 8 and the second three-way valve 9 to achieve preferential cooling of a certain battery module.

[0034] The function of this method is to dynamically identify abnormally overheated cells or modules by calculating the extreme temperature difference ΔT inside the battery module and the extreme temperature difference ΔTga between the modules in real time, and to achieve the composite liquid cooling control target of a one-series-multiple-parallel architecture through the on-off adjustment of the first three-way valve 8 and the second three-way valve 9, thereby directional distribution of the coolant flow, achieving targeted cooling of high-risk areas and balanced coordinated control of the full-package temperature, thereby suppressing the risk of thermal runaway, optimizing cooling energy efficiency, and ultimately improving the overall performance, life and safety of the battery system.

[0035] Among them, S1 obtains the surface temperature of each battery cell in the battery pack at a specific moment in real time, provides the raw data basis for temperature monitoring, and is the input source for all subsequent calculations. Its data accuracy directly affects the accuracy of system control. S2 calculates the temperature difference extreme value ΔT between the battery cells inside the battery module to quantify the temperature uniformity inside the module. Excessive ΔT may cause local thermal runaway or life degradation, and is a key indicator for triggering priority cooling; obtaining the maximum battery module temperature difference extreme value is used to quickly lock the target module with the highest current thermal runaway risk level; S3 is used to analyze the temperature distribution of each battery module to reflect the overall thermal state of the battery module. S4 is used to quantify the degree of imbalance in the global thermal distribution of the battery pack. By calculating the difference ΔTga between the maximum and minimum values ​​in the mean temperature of all battery modules, it reveals the degree of discreteness of the overall temperature between modules, provides a system-level thermal balance criterion for the cooling decision of S5, and then cooperates with ΔT to determine whether there are high-risk modules that need priority cooling. S5 is used to dynamically determine cooling priority based on the dual criteria of the module's internal temperature difference extreme value ΔT and the inter-module temperature difference extreme value ΔTga: when ΔT exceeds the set threshold value β, the battery module corresponding to the largest battery module temperature difference extreme value is immediately locked to block the risk of thermal runaway; when ΔT does not exceed β but ΔTga exceeds the threshold value γ, the battery module corresponding to the largest battery module temperature average value is located for priority cooling; when both parameters are safe, it indicates that the battery cells in the battery module are in a normal overheating state, and the temperature distribution of the battery cells inside and between modules is uniform with a small temperature difference. At this time, priority cooling is not required, and only normal cooling needs to be maintained. S6 is used to convert the cooling priority decision of S5 into real-time dynamic regulation 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, and the cooling flow is directed to the high-risk modules.

[0036] In an alternative embodiment, the step S2 includes the following steps: S21, extracting the maximum temperature value Tma of the battery cells in each battery module at time nt; S22, extracting the lowest temperature value Tmi of the battery cells in each battery module at time nt; S23. Calculate the temperature difference between the cells in each battery module at time nt using the following formula:

[0037] Wherein, nt represents the data sampling period of t seconds, the number of periods is n and n=0, 1, 2, etc., ΔT(m,nt) is the extreme temperature difference between the cells of the m-th battery module during the charge and discharge operation at the nt-th second, Tma(m,nt) is the maximum surface temperature of the cells in the m-th battery module during the charge and discharge operation at the nt-th second, and Tmi(m,nt) is the minimum surface temperature of the cells in the m-th battery module during the charge and discharge operation at the nt-th second; S24. Extract the maximum battery module temperature difference extreme value:

[0038] Among them, ΔT(i,nt) is the extreme temperature difference between the cells of the i-th battery module during charging and discharging at the nt-th second, which is the maximum temperature difference among all battery modules; ΔT(1,nt) is the extreme temperature difference between the cells of the No. 1 battery module during charging and discharging at the nt-th second, and ΔT(2,nt) is the extreme temperature difference between the cells of the No. 2 battery module during charging and discharging at the nt-th second.

[0039] The maximum and minimum temperature values ​​are used to identify temperature anomalies within each battery module (such as locally overheated cells), providing key data for thermal runaway risk warning. The temperature difference extreme value ΔT is used to quantify the degree of thermal imbalance within the module, serving as the core basis for determining the priority cooling strategy in S5. When ΔT exceeds a certain threshold β, it indicates that there is a high heat load module that requires priority cooling. The maximum battery module temperature difference extreme value is used to accurately lock 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 battery module temperature difference extreme value.

[0040] In an alternative embodiment, the calculation formula for the average temperature Tga of the battery module at time nt in S3 is:

[0041] Wherein, nt indicates that the data sampling period is t seconds, the number of periods is n and n=0, 1, 2, etc., Tga(m,nt) is the average surface temperature of the battery cells of the m-th battery module during charging and discharging at the nt-th second, Ts(m,1,nt) is the surface temperature value of the No. 1 battery cell of the m-th battery module collected during charging and discharging at the nt-th second, Ts(m,2,nt) is the surface temperature value of the No. 2 battery cell of the m-th battery module collected during charging and discharging at the nt-th second, Ts(m,Nm,nt) is the surface temperature value of the No. Nm battery cell of the m-th battery module collected during charging and discharging at the nt-th second, and Nm is the number of battery cells contained in the m-th battery module.

[0042] The battery module's temperature average Tga takes the arithmetic mean of the temperatures of all battery cells in the module to characterize the module's average thermal level. It also provides data support for S4 to calculate the temperature extreme difference ΔTga between modules, revealing system-level thermal distribution imbalances.

[0043] In an alternative embodiment, the S4 includes the following steps: S41. Extract the maximum average battery module temperature at time nt:

[0044] Wherein, nt represents the data sampling period of t seconds, the number of periods is n and n=0, 1, 2, etc., Tga(j,nt) is the average temperature between the cells of the j-th battery module during the charge and discharge operation at the nt-th second, which is the maximum value among the average temperatures of all battery modules; Tga(1,nt) is the average surface temperature of the cells of the 1-th battery module during the charge and discharge operation at the nt-th second; Tga(2,nt) is the average surface temperature of the cells of the 2-th battery module during the charge and discharge operation at the nt-th second; Tga(m,nt) is the average surface temperature of the cells of the m-th battery module during the charge and discharge operation at the nt-th second; S42. Extract the minimum average battery module temperature at time nt:

[0045] Wherein, Tga(k,nt) is the average temperature between the cells of the k-th battery module during the charge and discharge operation at the nt-th second, and is the minimum value among the average temperatures of all battery modules; S43. Calculate the temperature range between the battery modules in the battery pack at time nt using the following formula:

[0046] Among them, ΔTga(nt) is the average temperature difference of all battery modules inside the battery pack during charging and discharging at the ntth second.

[0047] The maximum and minimum average battery module temperatures are used to locate the focus of system-level thermal risks and lock in the module with the highest overall temperature rise in the entire pack; the temperature average 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 decision. When ΔTga exceeds the threshold γ, it indicates that there is a high-heat load module that needs to be cooled first, thereby coordinating with the local temperature difference data of S2 to form a three-level thermal risk prevention and control system of "cell-module-system".

[0048] In an alternative embodiment, the method for determining the battery module that needs priority cooling at time nt in S5 is: Case 1: If the temperature difference between the cells inside the battery module is greater than the critical temperature difference β inside the battery module, the battery module corresponding to the largest temperature difference between the cells ΔT(i,nt) is cooled first, i.e., battery module number i. Case 2: If the temperature difference between the cells inside all battery modules ΔT≤ the temperature difference threshold β, and the temperature difference between the battery modules inside the battery pack ΔTga> the temperature difference threshold γ, then the battery module corresponding to the largest average battery module temperature Tga(j,nt), that is, battery module number j, is cooled first. Case 3: If the temperature difference between the cells in all battery modules ΔT≤ the temperature difference threshold β within the battery module, and the average temperature difference between the battery modules in the battery pack ΔTga≤ the temperature difference threshold γ between the battery modules, then there is no battery module that requires priority cooling; Wherein, ΔT(i,nt) is the extreme temperature difference between the cells of the i-th battery module during charging and discharging at the nt-th second, which is the maximum value among the extreme temperature differences of all battery modules; Tga(j,nt) is the average temperature between the cells of the j-th battery module during charging and discharging at the nt-th second, which is the maximum value among the average temperatures of all battery modules.

[0049] The critical temperature difference β within the battery module and the critical temperature difference γ between battery modules can be set based on the battery pack thermal management design requirements, generally ≤ 5°C for β and ≤ 5°C for γ. Smaller β and γ values ​​indicate a higher requirement for temperature consistency within the battery pack. At the same time, these values ​​should be kept small, as otherwise, the temperature difference will increase, resulting in poor consistency and a shorter service life.

[0050] The dual criteria of internal module temperature difference extreme value ΔT and inter-module temperature difference extreme value ΔTga are introduced to determine whether there are abnormally overheated cells within a battery module. If ΔT > β, there are abnormally overheated cells within the module, indicating a high-risk module. If the abnormally overheated cells are not adequately cooled, their temperature will continue to rise, potentially accelerating their aging, causing more serious internal short circuits, and ultimately significantly increasing the risk of thermal runaway. Therefore, in this case, the battery modules corresponding to the largest module temperature difference extreme value ΔT(i,nt) should be prioritized for cooling to prevent the chain reaction caused by local overheating. If ΔT ≤ β, but ΔTga > γ, there is systematic temperature stratification between modules, indicating potential risk modules. If this stratification is not balanced over a long period of time, it may lead to further inconsistency in the battery pack, which in turn may trigger a chain reaction of accelerated local aging, shortened overall battery life, and increased charging and discharging safety risks. Therefore, in this case, the battery modules corresponding to the largest module temperature average value Tga(j,nt) should be prioritized for cooling to prevent further inconsistency in the battery pack. In principle, as long as ΔT≤β and ΔTga≤γ, it means that all the battery cells inside the module are normally overheated, and the overheating temperatures are basically the same. At this time, there are no battery cells with abnormally overheated temperatures in the battery module, and each battery module can be cooled indiscriminately, which can enable the system to operate in a more balanced and energy-saving manner without overcooling individual points, thereby optimizing system efficiency. In addition, for the execution of the above three situations, situation one is cooled first, then situation two, and finally situation three. In summary, the above-mentioned discrimination method divides thermal risks into three levels: high risk, potential risk, and safe state through the dual thresholds of β and γ. The constructed three-level thermal risk dynamic decision-making mechanism can realize the precise and targeted deployment of cooling resources, thereby effectively avoiding the risk of internal short circuit or even thermal runaway caused by local overheating, preventing accelerated local battery aging, and extending the overall service life of the battery pack.

[0051] In an alternative embodiment, in 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: When there is a battery module that needs priority cooling, the first three-way valve 8 only fully opens the passage between the inlet main pipe 1 and the auxiliary main pipe 6, so that 100% of the coolant flows into the auxiliary main pipe 6. The second three-way valve 9 corresponding to the battery module that needs priority cooling only fully opens the passage between the auxiliary branch pipe 7 and the outflow branch pipe 4, so that all the coolant flows to the risk module, and the risk module is fully cooled; 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, and the opening degree is At this time, a liquid cooling path with a serial and multi-parallel structure is formed. The second three-way valves 9 corresponding to the remaining battery modules are partially open to ensure that the flow through the remaining liquid cooling plates is equal. If the remaining second three-way valves 9 are fully open, the flow through the remaining liquid cooling plates may be unequal. When there is no battery module that needs to be cooled first, the first three-way valve 8 only fully opens the passage between the inflow main pipe 1 and the inflow branch pipe 2; the second three-way valve 9 corresponding to all battery modules only partially opens the passage between the outflow branch pipe 4 and the outflow main pipe 5, and the opening degree is , the coolant is evenly distributed to each parallel branch; where m is the number of battery modules.

[0052] Example Taking a battery pack consisting of 48 square lithium-ion cells as an example, the battery pack contains 6 battery modules, each of which is composed of 8 cells connected in series. It is charged at a 3C rate at an ambient temperature of 30°C. By collecting the battery cell operating temperature data at a certain moment in the charging process, the method flow of this technology is analyzed and introduced in detail.

[0053] S1. Collect the operating temperature data of each battery cell; The surface temperature data of each battery cell at a certain moment (set as time nt) during the charging process is collected, as shown in Table 1 below: Table 1

[0054] S2. Calculate the maximum temperature difference of each battery module; Calculate the maximum temperature value, minimum temperature value, and temperature difference between cells of each battery module during charging and discharging at the ntth second, as shown in Table 2 below: Table 2

[0055] Therefore, the maximum battery module temperature difference extreme value can be extracted from Table 2 as 3.2°C, which is the temperature difference extreme value between the cells of battery module No. 4 during charging and discharging at the nt second, and is the maximum value among all battery module temperature difference extreme values.

[0056] S3. Calculate the average temperature of each battery module; Calculate the average cell surface temperature of each battery module during charging and discharging at nt seconds, as shown in Table 3 below: Table 3

[0057] S4. Calculate the average temperature range of the battery module; From Table 3 above, we can extract the maximum average battery module temperature of 45°C, which is the average temperature between the cells of battery module No. 4 during charge and discharge at nt seconds. The minimum average battery module temperature is 40.6°C, which is the average temperature between the cells of battery module No. 1 during charge and discharge at nt seconds. Therefore, we can calculate the range of the average temperature of all battery modules during charge and discharge at nt seconds: ΔTga(nt) = 45°C - 40.6°C = 4.4°C.

[0058] S5. Determine and prioritize cooling of the battery module; Set the critical temperature difference β within the battery module to 3°C, and the critical temperature difference γ between battery modules to 1°C. Since the temperature difference of the battery cells within the battery module is ΔT(4,nt) = 3.2°C, which is greater than the critical temperature difference β within the battery module, the priority cooling battery module is battery module No. 4.

[0059] S6, dynamically controlled composite liquid cooling path; Since there are battery modules that need priority cooling, the specific control relationship of the composite liquid cooling path of the power battery pack during charging and discharging in the n+1th cycle is as follows: the AC end of the first three-way valve 8 is fully conductive, and the AB end is cut off; the ac end of the second three-way valve 9 of the No. 4 battery module is fully conductive, and the ab end is cut off. At this time, the No. 4 battery module can be cooled preferentially and quickly; the ab end of the second three-way valve 9 of the No. 1, 2, 3, 5, and 6 battery modules are partially conductive (with an opening degree of 20%), and the ac end is cut off, and the No. 1, 2, 3, 5, and 6 battery modules are cooled in parallel with the same coolant flow rate.

[0060] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: The present invention provides a composite dynamic liquid cooling control system and method for a power battery pack. By monitoring abnormally overheated cells or battery modules in the power battery pack and cooling them preferentially, it can effectively eliminate local overheating hot spots 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 differences between each battery module of the battery pack are kept within a certain range under overheating conditions during charging and discharging, effectively suppressing battery attenuation caused by local overheating, preventing accelerated local battery aging, and extending the overall service life of the battery pack.

[0061] The present invention is not limited to the aforementioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A composite dynamic liquid cooling control system for a power battery pack, characterized by: It includes temperature data acquisition module, calculation module and composite liquid cooling control module; The temperature data acquisition module is used to collect surface temperature data of each battery cell at different times during charging and discharging operation; The calculation module is used to receive the surface temperature data from the temperature data acquisition module, and calculate and determine the battery module in the battery pack that needs to be cooled first based on the surface temperature data; The composite liquid cooling control module comprises an inflow main pipe (1) and an outflow main pipe (5), a plurality of parallel battery liquid cooling assemblies (3) are connected between the inflow main pipe (1) and the outflow main pipe (5), the battery liquid cooling assembly (3) comprises 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 the liquid cooling device is connected 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 a plurality of parallel auxiliary branch pipes (7), and each of the auxiliary branch pipes (7) is respectively connected to one of the outflow branch pipes (4) through a second three-way valve (9); the composite liquid cooling control module also comprises a control component, the control component is used to receive the determination 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 hybrid dynamic liquid cooling control system for a power battery pack according to claim 1, characterized in that: The temperature data acquisition module is connected to a plurality of temperature sensors, and each of the temperature sensors is correspondingly connected to a battery cell.

3. The hybrid dynamic liquid cooling control system for a power battery pack according to claim 1, wherein: The calculation module includes a temperature difference extreme value calculation unit, a temperature mean calculation unit, a temperature mean extreme value calculation unit, and a priority cooling module determination unit; the temperature difference extreme value calculation unit is used to calculate the temperature difference extreme value between the battery cells inside each battery module based on the surface temperature data of each battery cell collected by the temperature data acquisition module, and obtain the maximum battery module temperature difference extreme value; the temperature mean calculation unit is used to calculate the temperature mean of the battery cells inside each battery module based on the surface temperature data of each battery cell collected by the temperature data acquisition module; the temperature mean extreme value calculation unit is used to calculate the temperature mean extreme value between the battery modules inside the battery pack based on the result of the temperature mean calculation unit; the priority cooling module determination unit is used to determine the battery module in the battery pack that needs priority cooling based on the results of the temperature difference extreme value calculation unit and the temperature mean extreme value calculation unit.

4. The hybrid dynamic liquid cooling control system for a power battery pack according to claim 1, wherein: The liquid cooling device is a liquid cooling plate, which is arranged on the heat exchange surface of the battery module. A liquid cooling channel is provided inside the liquid cooling plate and passes through the liquid cooling plate. The liquid cooling channel is used to achieve cooling by performing heat exchange 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).

5. A composite dynamic liquid cooling control method for a power battery pack, characterized by: The method is used to control the composite dynamic liquid cooling control system of the power battery pack according to any one of claims 1 to 4, comprising the following steps: S1, collecting the surface temperature data Ts of each battery cell at a certain moment; S2. Calculate the temperature difference extreme value ΔT between the battery cells in each battery module at that moment and the maximum battery module temperature difference extreme value based on the data collected in S1; S3. Calculate the average temperature Tga of each battery module at that moment based on the data collected in S1; S4. Calculate the temperature range difference ΔTga between battery modules in the battery pack using the data calculated in S3; S5. Determine the battery module that needs to be cooled first based on the temperature difference extreme value ΔT between the battery cells in the battery module and the temperature mean extreme value ΔTga between the battery modules in the battery pack; S6. Based on the determination result of S5, the valve ports of the first three-way valve (8) and the second three-way valve (9) are controlled and adjusted to achieve preferential cooling of a certain battery module.

6. The hybrid dynamic liquid cooling control method for a power battery pack according to claim 5, characterized in that: The S2 comprises the following steps: S21, extracting the maximum temperature value Tma of the battery cells in each battery module at time nt; S22, extracting the lowest temperature value Tmi of the battery cells in each battery module at time nt; S23. Calculate the temperature difference between the cells in each battery module at time nt using the following formula: Wherein, nt represents the data sampling period of t seconds, the number of periods is n and n=0, 1, 2, etc., ΔT(m,nt) is the extreme temperature difference between the cells of the m-th battery module during the charge and discharge operation at the nt-th second, Tma(m,nt) is the maximum surface temperature of the cells in the m-th battery module during the charge and discharge operation at the nt-th second, and Tmi(m,nt) is the minimum surface temperature of the cells in the m-th battery module during the charge and discharge operation at the nt-th second; S24. Extract the maximum battery module temperature difference extreme value: Among them, ΔT(i,nt) is the extreme temperature difference between the cells of the i-th battery module during charging and discharging at the nt-th second, which is the maximum temperature difference among all battery modules; ΔT(1,nt) is the extreme temperature difference between the cells of the No. 1 battery module during charging and discharging at the nt-th second, and ΔT(2,nt) is the extreme temperature difference between the cells of the No. 2 battery module during charging and discharging at the nt-th second.

7. The hybrid dynamic liquid cooling control method for a power battery pack according to claim 5, wherein: The calculation formula for the average temperature Tga of the battery module at time nt in S3 is: Wherein, nt indicates that the data sampling period is t seconds, the number of periods is n and n=0, 1, 2, etc., Tga(m,nt) is the average surface temperature of the battery cells of the m-th battery module during charging and discharging at the nt-th second, Ts(m,1,nt) is the surface temperature value of the No. 1 battery cell of the m-th battery module collected during charging and discharging at the nt-th second, Ts(m,2,nt) is the surface temperature value of the No. 2 battery cell of the m-th battery module collected during charging and discharging at the nt-th second, Ts(m,Nm,nt) is the surface temperature value of the No. Nm battery cell of the m-th battery module collected during charging and discharging at the nt-th second, and Nm is the number of battery cells contained in the m-th battery module.

8. The hybrid dynamic liquid cooling control method for a power battery pack according to claim 5, wherein: The S4 comprises the following steps: S41. Extract the maximum average battery module temperature at time nt: Wherein, nt represents the data sampling period of t seconds, the number of periods is n and n=0, 1, 2, etc., Tga(j,nt) is the average temperature between the cells of the j-th battery module during the charge and discharge operation at the nt-th second, which is the maximum value among the average temperatures of all battery modules; Tga(1,nt) is the average surface temperature of the cells of the 1-th battery module during the charge and discharge operation at the nt-th second; Tga(2,nt) is the average surface temperature of the cells of the 2-th battery module during the charge and discharge operation at the nt-th second; Tga(m,nt) is the average surface temperature of the cells of the m-th battery module during the charge and discharge operation at the nt-th second; S42. Extract the minimum average battery module temperature at time nt: Wherein, Tga(k,nt) is the average temperature between the cells of the k-th battery module during the charge and discharge operation at the nt-th second, and is the minimum value among the average temperatures of all battery modules; S43. Calculate the temperature range between the battery modules in the battery pack at time nt using the following formula: Among them, ΔTga(nt) is the average temperature difference of all battery modules inside the battery pack during charging and discharging at the ntth second.

9. The hybrid dynamic liquid cooling control method for a power battery pack according to claim 5, wherein: The method for determining the battery module that needs to be cooled first at time nt in S5 is: Case 1: If the temperature difference between the cells inside the battery module is greater than the critical temperature difference β inside the battery module, the battery module corresponding to the largest temperature difference between the cells ΔT(i,nt) is cooled first, i.e., battery module number i. Case 2: If the temperature difference between the cells inside all battery modules ΔT≤ the temperature difference threshold β, and the temperature difference between the battery modules inside the battery pack ΔTga> the temperature difference threshold γ, then the battery module corresponding to the largest average battery module temperature Tga(j,nt), that is, battery module number j, is cooled first. Case 3: If the temperature difference between the cells in all battery modules ΔT≤ the temperature difference threshold β within the battery module, and the average temperature difference between the battery modules in the battery pack ΔTga≤ the temperature difference threshold γ between the battery modules, then there is no battery module that requires priority cooling; Wherein, ΔT(i,nt) is the extreme temperature difference between the cells of the i-th battery module during charging and discharging at the nt-th second, which is the maximum value among the extreme temperature differences of all battery modules; Tga(j,nt) is the average temperature between the cells of the j-th battery module during charging and discharging at the nt-th second, which is the maximum value among the average temperatures of all battery modules.

10. The hybrid dynamic liquid cooling control method for a power battery pack according to claim 5, wherein: In said 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: When there is a battery module that needs to be cooled first, the first three-way valve (8) only 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 that needs to be cooled first only 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 remaining battery modules only partially open the passage between the outflow branch pipe (4) and the outflow main pipe (5), and the opening degrees are all ; When there is no battery module that needs to be cooled first, the first three-way valve (8) only 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.

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