Flow control method and system for electric vehicle-mounted power battery liquid cooling system

Abstract

The invention belongs to the technical field of power battery cooling, and particularly relates to a flow control method and system for a liquid cooling system of an electric vehicle-mounted power battery, and the method comprises the steps: carrying out the parameterization of a geometric model of the liquid cooling system; establishing an equipment resistance model based on the equipment flow resistance characteristics; initializing flow distribution, constructing a dynamic flow distribution model, calculating the flow of each node and judging whether the flow meets a target requirement or not, and if not, readjusting the flow; calculating the resistance of each section, determining the total resistance of the pipeline, and checking the water pump lift; the flow uniformity is judged by calculating the pipeline resistance between the nodes, and if the flow is not uniform, the flow is redistributed or the pipeline design is optimized until the flow is uniform. Through flow control, the problems of non-uniform flow distribution and poor temperature consistency of multiple battery packs in the prior art are solved, the optimal working state of the power battery is ensured, overheating and overlarge temperature difference are avoided, and the operation efficiency, stability, durability and safety are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of power battery cooling, and in particular, relates to a flow control method and system for a liquid cooling system of a power battery onboard an electric vehicle. Background Art

[0002] In electric vehicles (especially pure electric buses), the temperature management of power batteries is crucial. Power batteries are prone to thermal runaway at high temperatures, leading to safety risks. At the same time, low temperature environments will affect their starting efficiency and charging and discharging performance. In order to ensure stable battery performance and extend battery life, power battery liquid cooling systems have gradually become the mainstream solution, which regulates the battery pack temperature through the circulation of coolant, thereby effectively managing the battery temperature in various environments.

[0003] Existing liquid cooling systems generally use ethylene glycol solution and other coolants to circulate in the battery internal circuit, and adjust the battery temperature through radiators and heating devices (such as PTC heaters). However, with the widespread application of multi-battery configurations in electric buses, liquid cooling systems still face many technical challenges in flow control and temperature consistency, which are specifically reflected in the following aspects:

[0004] 1. Flow control and temperature balance issues: In a multi-battery system, the difference in battery position and distance to the cooling equipment makes it difficult to evenly distribute the coolant flow, resulting in a large temperature difference between the batteries, which can easily lead to inconsistent performance and accelerate battery capacity decay, and may even trigger the risk of thermal runaway. For example, patent CN113809440B discloses a liquid-cooled power battery coolant flow control method, system and vehicle. This technical solution controls the flow through a temperature difference relationship, but this method relies on complex three-dimensional computational fluid dynamics simulation, which has high costs in the design stage and low optimization efficiency. At the same time, the solution lacks effective support for the flow distribution problem of multi-battery parallel structures, and fails to solve the temperature difference problem caused by uneven flow.

[0005] 2. Control complexity of multi-functional temperature management: Existing systems usually integrate multiple components (such as electronic water pumps, heat exchangers and compressors) to achieve dynamic temperature control, but in the case of multiple batteries in parallel, the problem of uneven flow distribution cannot be solved, and frequent mode switching increases the system design cost and control difficulty. For example, patent CN116198275A describes an electric vehicle air conditioning and power battery thermal management control system and control method. Although the system described in this technical solution has cooling and heating functions, the problem of uneven flow distribution is still difficult to solve when multiple batteries are connected in parallel. In addition, in a multi-battery scenario, the system needs to frequently switch cooling and heating modes according to changes in battery temperature, which significantly increases the complexity of system design. This difficulty has not been effectively solved in existing solutions, which increases the system design cost and control difficulty.

[0006] 3. Limitations of flow monitoring: In the prior art, patent CN118054039A discloses a flow monitoring method for a liquid flow battery system. This flow monitoring method is mainly based on the head-flow relationship of a centrifugal pump to monitor the coolant flow, but its focus is on the performance of the water pump and fails to consider the flow balance requirements of a multi-battery system. Another is a variable pressure difference control method, such as patent CN112665237B discloses a chilled water system flow control method, device and chilled water system. Although it is suitable for a chilled water system, it is not good at multi-loop flow balance control in a multi-battery liquid cooling system and cannot meet the requirements of multi-battery configurations of pure electric buses. Therefore, the existing monitoring methods cannot reflect the flow distribution of each battery in real time and accurately, and thus cannot effectively optimize flow balance.

[0007] In general, these technical solutions all have limitations in flow control and cannot achieve uniform flow distribution among multiple batteries. It is difficult to meet the optimization requirements for temperature consistency and flow control in multi-battery systems. There is an urgent need for a more efficient and low-cost flow control method to ensure the temperature uniformity and safety performance of the power battery system. Summary of the invention

[0008] In view of the defects of the prior art, the present invention proposes a flow control method and system for a liquid cooling system of a power battery on an electric vehicle. The method controls the flow of the liquid cooling system of the power battery to ensure that the power battery operates in the best working state, avoids battery overheating or uneven temperature distribution of multiple battery packs, and improves its operating efficiency, stability, durability and safety. The method can facilitate the control optimization of the thermal management system of the battery liquid cooling system during the design stage, reducing development time and costs.

[0009] In one aspect, the present invention provides a flow control method for a liquid cooling system of a power battery on an electric vehicle, the method comprising:

[0010] Step 1: Parameterize the geometric model of the power battery liquid cooling system;

[0011] Step 2: Establishing a device resistance model based on the flow resistance characteristic data of the device of the power battery liquid cooling system;

[0012] Step 3: Allocate the initialization system flow, build a dynamic flow distribution model based on the flow relationship between nodes at all levels, calculate the flow through each level of nodes, and determine whether the flow reaching the battery meets the target requirements. If it meets the target requirements, execute the next step. If it does not meet the target requirements, readjust the initial flow according to step 1;

[0013] Step 4: Calculate the actual resistance of each section of the system based on the flow distribution in step 3;

[0014] Step 5: According to the system segmented resistance, determine the total pipe resistance of the complete circulation path from the water pump outlet to the farthest battery pack and then back to the water tank. Determine the total system resistance through the total pipe resistance and equipment resistance. Verify whether the water pump head meets the system total resistance requirements through the system total resistance.

[0015] Step 6: Determine the flow uniformity by calculating the pipe resistance between nodes. If it is uneven, redistribute the flow or optimize the pipeline design until the flow of all battery packs is uniform.

[0016] Furthermore, in step 1, the parameters of the geometric model of the power battery liquid cooling system include each shunt node, the equipment inlet flow Q in,k , Equipment export flow Q out,k , Pipeline length l i,j , pipe diameter d i,j 、Pipeline accessories resistance coefficient ε i,j and the preset initialization system flow Q 泵 .

[0017] Furthermore, in step 1, the coolant outlet of the PTC heater of the power battery liquid cooling system is node 1. Starting from node 1, the coolant is diverted to different branches of node 2. Starting from each branch of node 2, the coolant is further diverted to different branches of node 3. Starting from each branch of node 3, the coolant is further diverted to different branches of the next node until each battery pack receives the coolant input from the corresponding node for heat exchange. After the coolant completes the heat exchange in the battery pack, it is gradually returned to the previous node through the reflux path, and finally the coolant returns to the water pump.

[0018] Furthermore, in step 2, the equipment resistance model is determined by the following formula:

[0019] H 设备 =aQ m +bQ m-1 +cQ m-2 +……+Q+k

[0020] Where: H 设备 Indicates equipment resistance, unit is Pa; Q indicates flow rate, unit is m 3 / s; m represents the number of fitting times; parameters a, b, c, ... k represent the fitting coefficients.

[0021] Further, step 3 includes:

[0022] Step 3.1: Build a dynamic traffic distribution model to define the traffic between nodes;

[0023] Step 3.2: Based on step 3.1, determine whether the battery flow rate reaches the target flow rate requirement. If it does, proceed to the next step to calculate the system segmented resistance. Otherwise, return to step 1 to reinitialize the system flow rate Q. 泵 .

[0024] Furthermore, in step 3.1, the dynamic traffic distribution model is determined by the following formula:

[0025] Q 换热器,泵 =Q 泵,PTC =Q PTC,1 =a×Q 1,2-1 =a×Q 1,2-2 =……=a×Q 1,2-a =ab×

[0026] Q 2-1,3-1 =ab×Q 2-1,3-2 =……=ab×Q 2-1,3-b =abc×Q 3-1,4-1 =abc×Q 3-1,4-2 =……=abc×Q 3-1,4-c =(abc……n)×Q n-m,电池k,n-m’ ;

[0027] Where: Q 换热器,泵 Indicates the flow rate from the heat exchanger to the pump; Q 泵,PTC Indicates the flow rate from the pump to the PTC; Q PTC,1 Indicates the traffic from PTC to node 1; Q 1,2-1 , Q 1,2-2 , Q 1,2-a They represent the flow of each branch node from node 1 to node 2; Q 2-1,3-1 , Q 2-1,3-2 、ab×Q 2-1,3-b They represent the flow from one of the branch nodes in node 2 to each branch node in node 3; Q 3-1,4-1 , Q 3-1,4-2 , Q 3-1,4-c They represent the flow from one of the branch nodes in node 3 to each branch node in node 4; Q n-m,电池k,n-m’ Indicates the flow with the kth battery; the flow of each node multiplied by a, b, c...n means that the flow will be multiplied by the diversion ratio coefficient in turn when passing through each level of nodes;

[0028] In step 3.2, it is determined whether the battery flow rate reaches the target flow rate requirement according to the following formula:

[0029] Q n-m,电池k,n-m’ >Q 目标

[0030] If Q n-m,电池k,n-m’ ≤Q 目标 , you need to readjust the system initial flow.

[0031] Furthermore, in step 4, the segmental resistance H of the i-th segment of the system i Determined by the following formula:

[0032]

[0033] in,

[0034] Where: H i represents the resistance of the i-th section, in Pa; v i Indicates the speed of the i-th segment, in m / s; d i Indicates the pipe diameter of the i-th section, in m; l i represents the length of the i-th segment, in m; ρ represents the density of the coolant, in kg / m 3 ; ε i Indicates the resistance coefficient associated with the pipe accessories; Q i Indicates the flow rate of the i-th section, in m 3 / s.v o (m 2 / s) represents the reference coefficient of equivalent kinematic viscosity relative to ethylene glycol, K o (m) represents the reference coefficient of the equivalent roughness height relative to the plastic pipe, which is preferably 1.

[0035] Further, step 5 comprises:

[0036] Step 5.1: Determine the complete circulation path from the water pump outlet to the farthest battery pack and then back to the water tank. Based on the system segmented resistance obtained in step 4, obtain the total resistance of the pipeline;

[0037] Step 5.2: Obtain the resistance of each device through the device resistance model in step 2, and combine it with the total pipeline resistance obtained in step 5.1 to obtain the total system resistance;

[0038] Step 5.3: If 0<(H 泵 -H 系统总 )<1m H2O, then determine the pump head H 泵 Initially meet H 系统总 According to the requirements, the flow rate Q is determined according to the performance curve of the water pump. 泵 and the pump head H 泵 Is it in the highest efficiency range? If it is within ±10% of the highest efficiency, then the pump head H is determined. 泵 Satisfy H 系统总 If it exceeds this range, return to step 1 to readjust the system initial flow Q 泵 , and repeat the calculation according to steps 1-5 until the system meets the requirements.

[0039] Further, step 6 comprises:

[0040] Step 6.1: Based on the pipeline resistance of each node obtained in step 4, define the maximum node pipeline resistance H max and the minimum node pipe resistance H min ;

[0041] Step 6.2: Determine the uniformity of the resistance of each pipeline. If (H max -H min ) / H min >10%, it means that the flow distribution is uneven, otherwise, if the uniformity meets the requirements, there is no need to adjust the flow;

[0042] Step 6.3: If the uniformity of pipeline resistance does not meet the requirements, redistribute the flow Q between node (m-1) and node (m) (m-1),m , otherwise let m = m-1 and determine the next node until m is the minimum number of nodes;

[0043] Step 6.4: If all battery flow rates meet Q 电池1 ≈Q 电池2 ≈…≈Q 电池k , the uniformity target is achieved. If not, optimize the pipeline design and redistribute the flow according to step 6.1.

[0044] On the other hand, the present invention also provides a flow control system for a liquid cooling system of a power battery on an electric vehicle, comprising:

[0045] A parameterized processing module, used for parameterizing the geometric model of the power battery liquid cooling system;

[0046] Resistance modeling module, used to establish equipment resistance model based on equipment flow resistance characteristic data of power battery liquid cooling system;

[0047] The flow distribution module is used to distribute the initialization system flow, build a dynamic flow distribution model based on the flow relationship between nodes at all levels, calculate the flow through each level of nodes, and determine whether the flow reaching the battery meets the target requirements;

[0048] Resistance calculation module, used to calculate the actual resistance of each section of the system based on flow distribution;

[0049] The total resistance verification module is used to determine the total resistance of the pipeline in the complete circulation path from the water pump outlet to the farthest battery pack and then back to the water tank according to the system segment resistance, and determine the total system resistance through the total resistance and equipment resistance to verify whether the water pump head meets the system total resistance requirements;

[0050] The uniformity judgment module is used to calculate the pipeline resistance between nodes and judge the flow uniformity. If it is uneven, the flow is redistributed or the pipeline design is optimized until the flow of all battery packs is uniform.

[0051] The beneficial effects of the present invention are:

[0052] First, the flow control method of the electric vehicle power battery liquid cooling system of the present invention, by establishing an equipment resistance model and a dynamic flow distribution model, can complete the flow design without relying on mature simulation software on the market, greatly saving simulation and optimization costs. The method combines the actual system resistance calculation with the water pump head verification, and comprehensively judges the uniformity of the pipeline resistance between nodes and optimizes the flow distribution to achieve precise control of the flow of multiple battery packs, ensure the uniformity of the cooling effect, improve the cooling efficiency and thermal balance ability, reduce energy consumption, and extend the battery life. The method is simple and efficient, adapts to the dynamic needs under different operating conditions, enhances the stability and economy of the system, and provides reliable support for the optimal design and operation of the liquid cooling system.

[0053] Second, in the preferred implementation, the present invention accurately defines each shunt node, pipeline parameters and equipment flow through the geometric model parameter design of the power battery liquid cooling system, ensuring that the coolant starts from the outlet of the PTC heater and passes through each shunt node in sequence to achieve reasonable shunt until it is evenly distributed to each battery pack for efficient heat exchange. At the same time, the coolant is recycled through the reflux path, thereby improving the thermal management efficiency, cooling uniformity and overall operating stability of the system.

[0054] Third, in the preferred implementation, the present invention accurately calculates the equipment resistance through the mathematical expression of the equipment resistance model, and combines the flow distribution model to clarify the flow distribution between nodes, ensuring that the coolant is proportionally distributed to each node and battery pack in the power battery liquid cooling system. At the same time, by judging whether the flow meets the target demand, the initial flow configuration of the system is dynamically adjusted and optimized, thereby improving the cooling efficiency and flow uniformity of the system, effectively improving the thermal management performance of the power battery, extending the battery life, and improving the overall operation stability and energy efficiency of the system.

[0055] Fourth, in the preferred implementation, the present invention uses a segmented resistance calculation formula to comprehensively consider the flow rate, diameter, length, coolant density and pipeline accessory resistance coefficient of the pipeline to accurately calculate the resistance distribution of each section of the pipeline.

[0056] Fifth, in the preferred implementation, the present invention ensures that the pump head matches the system requirements by clarifying the complete circulation path of the power battery liquid cooling system, and comprehensively calculating and verifying the system segment resistance, equipment resistance and total resistance. At the same time, by judging whether the water pump working point is in the optimal efficiency range, the water pump operation efficiency and system energy efficiency are improved. If the head is not satisfied or the working point deviates from the optimal range, the initial flow configuration can be dynamically adjusted to optimize the system design, and ultimately achieve efficient operation of the liquid cooling system and balance and reliability of battery thermal management.

[0057] Sixth, in the preferred implementation, the present invention accurately determines the uniformity of the pipeline resistance of each node through the calculation based on the pipeline resistance. If the resistance difference is found to exceed the preset threshold, the distribution of the coolant flow is dynamically adjusted to ensure uniform flow distribution. Furthermore, by iteratively optimizing the flow distribution and pipeline design, the uniformity of the coolant distribution between the battery packs can be effectively improved, avoiding the problem of overcooling or overheating caused by uneven flow, thereby improving the thermal management performance and operating stability of the system and extending the service life of the battery pack.

[0058] Seventh, the flow control system for the electric vehicle power battery liquid cooling system of the present invention realizes dynamic optimization and uniform distribution of the flow of the electric vehicle power battery liquid cooling system through collaboration between various modules to meet the battery target flow requirements and ensure flow uniformity, while optimizing the pipeline design and checking the matching of the system resistance and water pump head. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 It is a flow chart of a flow control method for a liquid cooling system of a power battery on an electric vehicle of the present invention;

[0060] Figure 2 Schematic diagram of a power battery liquid cooling system containing multiple battery packs according to an embodiment of the present invention. DETAILED DESCRIPTION

[0061] In order to enable those skilled in the art to better understand the technical solution of the present application, the present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0062] In the description of this application, the terms "first", "second", and "third" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance; the term "plurality" refers to two or more, unless otherwise expressly defined. Terms such as "installed", "connected", "connected", and "fixed" should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0063] In the description of the present application, it should be understood that the directions or positional relationships indicated by the terms "up", "down", "left", "right", "front", "back", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or unit referred to must have a specific direction, be constructed and operated in a specific orientation, and therefore, should not be understood as a limitation on the present application.

[0064] In the description of this specification, the description of the terms "one embodiment / method", "some embodiments / methods", "specific embodiments / methods", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / method or example are included in at least one embodiment / method or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment / method or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments / methods or examples in a suitable manner.

[0065] As the instruction manual Figure 1 The present invention provides a flow control method for a liquid cooling system of a power battery on an electric vehicle, the method comprising:

[0066] Step 1: Parameterize the geometric model of the power battery liquid cooling system.

[0067] The purpose of step 1 is to initialize and define the key parameters of the power battery liquid cooling system to provide a basis for subsequent calculations. This step determines the basic geometric structure and initial parameter conditions of the power battery liquid cooling system.

[0068] As the instruction manual Figure 2The power battery liquid cooling system mainly includes a water pump 1, a PTC heater 2, a battery, a heat exchanger 5, a water tank 6 and a diversion node. The coolant in the water tank 6 flows through the water pump 1 to the PTC heater 2, where it is heated. The heated coolant is diverted through each distribution node (for example, nodes 1, 2, 3, etc.) and enters different paths. The water pump 1 is usually set at the inflow end of the system and connected to the mainstream pipeline in the liquid cooling system to drive the coolant to circulate throughout the liquid cooling system to ensure that the coolant can continue to flow through each component, thereby taking away the heat of the battery. The PTC heater 2 is set at the rear end of the water pump 1 and connected to the pipeline flowing to the battery to preheat the coolant when the ambient temperature is low to ensure that the coolant will not affect the battery performance due to the low temperature when entering the battery. The battery is connected after the PTC heater 2, and is usually designed with a cooling pipe (or cooling plate) structure. It is the core heat source component of the power battery liquid cooling system and the main cooling target of the coolant. The battery generates a lot of heat when working. The coolant flows through the inside of the battery and takes away the heat by convection to maintain the temperature of the battery stable. The heat exchanger 5 is arranged behind the battery and connected to the battery through a pipe. It is used to transfer the heat absorbed by the coolant from the battery to the external environment, thereby reducing the temperature of the coolant and realizing a closed loop of the cooling cycle. The shunt node refers to a special position in the coolant flow path, where the coolant is divided into multiple branches to flow to different devices or areas. In the power battery liquid cooling system, multiple batteries or areas usually require coolant for heat dissipation. The shunt node distributes the coolant to each battery or area by shunt to ensure that they are properly cooled. The setting position of the shunt node in the power battery liquid cooling system includes setting the shunt node after the PTC heater 2, before the coolant flows into each battery, and before the coolant flows out of each battery and enters the heat exchanger 5. The shunt node can work in conjunction with the control valve to control the flow distribution of the coolant by adjusting the opening of the valve to ensure that the coolant can be distributed to each branch as required.

[0069] When defining the geometric model parameters of the power battery liquid cooling system, it is necessary to ensure that these parameters can fully describe the geometric structure of the liquid cooling system and the flow path of the coolant, so as to provide complete basic data for subsequent fluid dynamics analysis and thermal analysis. The parameters of the system geometric model include each branch node, the equipment inlet flow Q in,k , Equipment export flow Q out,k , Pipeline length l i,j , pipe diameter d i,j 、Pipeline accessories resistance coefficient ε i,j and the preset initialization system flow Q 泵 .

[0070] First, mark the number of each diversion node. Figure 1Taking the battery liquid cooling system shown as an example, the coolant outlet of the PTC heater 2 is marked as node 1. There are multiple sections of pipelines from node 1 to the coolant inlet of each battery. Multiple shunt nodes are set in sequence according to the number of pipeline sections, that is, starting from node 1, the heated coolant is shunted to different branches of node 2: node 2-1, node 2-2...node 2-a. Starting from each branch of node 2, the coolant is further shunted to different branches of node 3, for example, node 2-1 is shunted to node 3-1, node 3-2...node 3-b respectively. Starting from each branch of node 3, the coolant is further shunted to different branches of the next node, for example, node 3-1 is shunted to node n-1, node n-2...node nm respectively. Finally, each battery group (battery 1 to battery k) receives the coolant input from the corresponding node for heat exchange, thereby achieving temperature regulation. For example, the coolant of node n-1 flows to battery 1, the coolant of node n-2 flows to battery 2, and the coolant of node nm flows to battery k.

[0071] After the coolant completes the heat exchange in the battery pack, it gradually returns to the corresponding node through the reflux path, and finally the coolant returns to the water tank to complete the cycle. For example: the coolant from battery 1 to battery k flows to the corresponding node (n-1)' to node (nm)', and nodes (n-1)' to node (nm)' respectively converge to different branch nodes (3-1)' to (3-b)' of node 3', and nodes (3-1)' to (3-b)' respectively converge to different branch nodes (2-1)' to (2-a)' of node 2', and nodes (2-1)' to (2-a)' respectively converge to node 1', and the coolant finally flows from node 1' to heat exchanger 5, which is connected to water tank 6 and air conditioning system, and air conditioning system is used for additional heating or cooling. This design enhances the adaptability of the system under different temperature control requirements.

[0072] Equipment inlet flow rate Q in,k and equipment outlet flow Q out,k Refers to the inlet and outlet flow of each device (such as water pump 1, PTC heater 2, heat exchanger 5, battery) to describe the fluid flow of the liquid cooling system. For example: the inlet flow of PTC heater 2 can be expressed as Q in,PTC , the outlet flow is Q out,PTC The flow rate of the equipment inlet and outlet is calculated according to the flow balance principle of the system during the system design stage. (n) =Q (n)' Indicates that the inlet and outlet flow rates of the coolant are equal at these nodes, satisfying the flow continuity. Define the flow distribution ratio of the coolant at each branch node (for example, 60% and 40% are distributed to different branches), Q out,1 = r1·Q total , Q out,2 = r2·Q total, where r1+r2=1, r1 and r2 represent the split ratio, Q total Indicates the total flow rate to ensure that coolant flows to each device as required.

[0073] Then, the length of the pipeline between each node is determined according to the position of each node. i,j Refers to the length of the pipeline between adjacent nodes i and j. This parameter is used to calculate the friction resistance and pressure drop of the fluid in the pipeline. For example, the length of the pipeline from the coolant pump 1 to the PTC heater 2 can be expressed as l 泵,PTC The coolant pipeline from PTC heater 2 to battery 1 passes through multiple flow nodes and can be represented as l PTC,1 , l 1,2-1 , l 2-1,3-1 …… n-1,电池1 The coolant pipeline from battery 1 to heat exchanger 5 passes through multiple flow nodes and can be represented as l 电池1,(n-1)’ …… (3-1)’,(2-1)’ , l (2-1)’,(1)’ , l (1)’,换热器 .

[0074] Pipe diameter d i,j Refers to the inner diameter (or flow diameter) of each section of the pipeline, which directly affects the flow rate and friction resistance of the fluid. For example: the diameter of the pipeline from water pump 1 to PTC heater 2 can be expressed as d 泵,PTC , the diameter of the pipe from PTC heater 2 to battery 1 can be expressed as d according to multiple shunt nodes. PTC,1 ,d 1,2-1 ,d 2-1,3-1 ……d n-1,电池1 The diameter of the pipe from battery 1 to heat exchanger 5 can be expressed as d according to multiple flow nodes. 电池1,(n-1)’ ……d (3-1)’,(2-1)’ ,d (2-1)’,(1)’ ,d (1)’,换热器 .

[0075] Pipeline accessories resistance coefficient ε i,j Refers to the ratio of the resistance and dynamic pressure generated by the fluid flowing through each pipe attachment. Pipes with more attachments will produce greater flow resistance. For example: the elbow attachment in the pipe path from water pump 1 to PTC heater 2 can be expressed as ε 泵,PTC , the multiple single attachment coefficients in the same section of the pipeline path are added to form the attachment resistance coefficient of this section of the pipeline. The pipeline attachment resistance coefficient from PTC heater 2 to battery 1 can be expressed as ε according to multiple shunt nodes. PTC,1 , ε 1,2-1 , ε 2-1,3-1 ……ε n-1,电池1 The resistance coefficient of the pipe attachment from battery 1 to heat exchanger 5 can be expressed as ε according to multiple flow distribution nodes. 电池1,(n-1)’ ……ε(3-1)’,(2-1)’ , ε (2-1)’,(1)’ , ε (1)’,换热器 .

[0076] Preset initialization system flow Q 冷却液泵 Refers to the liquid flow rate set by the system during the initial filling or startup phase of the coolant, which is used to ensure that the entire liquid cooling system can operate normally according to the design requirements and provide benchmark data for subsequent fluid dynamics and thermodynamics analysis. By initializing the flow rate, it is verified whether the flow distribution of each pipeline is reasonable to ensure that key components (such as batteries) can obtain sufficient coolant flow.

[0077] In the implementation of the present application, the length and diameter of each section of the pipeline can be measured on the three-dimensional model of the power battery liquid cooling system using CAD software (such as AutoCAD, SolidWorks). The resistance coefficient of the pipeline accessories can be found in the fluid mechanics book according to the type of pipeline accessories. The geometric model of the system is parameterized by three-dimensional design software, and the parameters of each component (such as device nodes, shunt nodes and the corresponding number of pipeline accessories) are set in Excel, code or developed program pages based on the process of the patented method to define the initialization system flow Q 冷却液泵 , set the pipe length, pipe diameter and resistance factor ε. Through the formula and process module in this patent, calculate the flow distribution of each equipment inlet and outlet, calculate the flow balance at the diversion node, and analyze the pressure loss of each section.

[0078] Step 2: Establish a device resistance model based on the flow resistance characteristic data of the equipment of the power battery liquid cooling system.

[0079] The purpose of step 2 is to establish an accurate mathematical model through the formulaic expression of the equipment characteristic data to describe the flow resistance relationship of each device in the cooling system (coolant pump, PTC, battery pack, heat exchanger 5, etc.), laying the foundation for subsequent fluid dynamics analysis, system optimization and operation status prediction.

[0080] Specifically, obtain the flow resistance characteristic curve of key equipment (such as water pump 1, PTC heater 2, battery pack cooling channel, heat exchanger 5) from the supplier. The curve is usually based on flow rate Q and equipment resistance H. 设备 The data extraction method uses a data acquisition tool (such as image digitization software or the original data table provided by the supplier) to extract discrete data points of the curve.

[0081] Use the polynomial fitting method to fit the flow resistance characteristic curve and construct the equipment resistance model:

[0082] H 设备 =aQ m +bQ m-1 +cQm-2 +……+Q+k(1)

[0083] Where: H 设备 Indicates equipment resistance, unit is Pa; Q indicates flow rate, unit is m 3 / s; m represents the number of fitting times, which is selected according to the complexity of the characteristic curve. Generally, m=3 can meet the requirements; parameters a, b, c, ... k represent fitting coefficients, which are obtained through optimization algorithms such as the least squares method.

[0084] Select the goodness of fit R 2 As the evaluation criteria for the fitting results, R 2 ≥0.95. Clearly define the data coverage, for example, the range of flow Q is Q min To Q max The original data (Q, H) collected from the experiment 设备 ) is organized into two columns of data tables, with flow rate Q as the independent variable and equipment resistance H as the 设备 is the dependent variable. Then select the equipment resistance model H 设备 , by gradually fitting polynomials of different orders, selecting the goodness of fit R 2 The polynomial is fitted using the least squares method to minimize the sum of squared errors.

[0085] Further evaluate the fitting results. First calculate the goodness of fit Calculate the absolute error |H 设备实际 -H 设备拟合 |, and calculate the relative error Verify whether the engineering requirements are met. 2 <0.95, by increasing or decreasing the order m of the polynomial, the fitted equipment resistance model formula and coefficients (a, b, c, ...) are finally stored in a database or document.

[0086] Step 3: Allocate the initialization system flow, build a dynamic flow distribution model based on the flow relationship between nodes at all levels, calculate the flow through each level of nodes, and determine whether the flow reaching the battery meets the target requirements. If it meets the target requirements, execute the next step. If it does not meet the target requirements, readjust the initial flow according to step 1.

[0087] The purpose of step 3 is to reasonably distribute the flow in the system to ensure that each node (especially the equipment at the end point, such as the battery pack) obtains the target flow that meets the demand and avoids substandard cooling or heating effects due to insufficient flow.

[0088] Step 3 includes:

[0089] Step 3.1: Build a dynamic traffic distribution model to define the traffic between nodes.

[0090] The dynamic traffic distribution model is determined by the following formula:

[0091] Q 换热器,泵 =Q 泵,PTC =Q PTC,1 =a×Q 1,2-1 =a×Q 1,2-2 =……=a×Q 1,2-a =ab×

[0092] Q 2-1,3-1 =ab×Q 2-1,3-2 =……=ab×Q 2-1,3-b =abc×Q 3-1,4-1 =abc×Q 3-1,4-2 =……=abc×Q 3-1,4-c =(abc……n)×Q n-m,电池k,n-m’ (2)

[0093] Where: Q 换热器,泵 Indicates the flow rate from the heat exchanger to the pump; Q 泵,PTC Indicates the flow rate from the pump to the PTC; Q PTC,1 Indicates the traffic from PTC to node 1; Q 1,2-1 , Q 1,2-2 , Q 1,2-a They represent the flow of each branch node from node 1 to node 2; Q 2-1,3-1 , Q 2-1,3-2 、ab×Q 2-1,3-b They represent the flow from one of the branch nodes in node 2 to each branch node in node 3; Q 3-1,4-1 , Q 3-1,4-2 , Q 3-1,4-c They represent the flow from one of the branch nodes in node 3 to each branch node in node 4; Q n-m,电池k,n-m’ Represents the flow to the kth battery; the flow of each node multiplied by a, b, c...n means that the flow will be multiplied by the diversion ratio coefficient in turn when passing through each level of nodes, forming a progressive flow relationship.

[0094] From formula (2), it can be seen that the flow rate from the heat exchanger to the pump is Q 换热器,泵 =Q 泵,PTC =Q PTC,1 The traffic from node 1 to node 2 is distributed as follows: Q PTC,1 =a×Q 1,2-1 , Q PTC,1 =a×Q 1,2-2 , ..., and so on to Q PTC,1 =a×Q 1,2-a Node 2 continues to allocate to node 3. Taking node 2-1 in node 2 as an example, a×Q 1,2-1 =ab×Q 2-1,3-1 , Q1,2-1 =ab×Q 2-1,3-2 , ..., and so on, gradually diverted to ab×Q 2-1,3-b After the traffic reaches node 3, it continues to be divided in proportion. Taking node 3-1 in node 3 as an example, ab×Q 2-1,3-1 =abc×Q 3-1,4-1 , Q 2-1,3-1 =abc×Q 3-1,4-2 , ..., until abc×Q 3-1,4-c This progressive relationship is maintained to the nth level node and finally flows to the battery pack, Q PTC,1 =(abc……n)×Q n-m,电池k,n-m’ .

[0095] The system can dynamically distribute the cooling / heating requirements of each battery pack by adjusting the diversion ratio (a, b, c...) of each level. This design ensures that each battery pack can obtain the appropriate fluid flow under different load conditions, thereby optimizing thermal management performance. Flow sensors can be arranged before and after each node for real-time monitoring and feedback to ensure accurate diversion ratios. Controllable valves are set at key nodes to adjust the diversion ratio coefficient according to real-time needs. By adjusting the main flow Q PTC,1 and diversion ratio to improve overall energy utilization.

[0096] Step 3.2: Based on step 3.1, determine whether the battery flow rate reaches the target flow rate requirement. If it does, proceed to the next step to calculate the system segmented resistance. Otherwise, return to step 1 to reinitialize the system flow rate Q. 冷却液泵 .

[0097] To determine whether the battery flow rate has reached the target flow rate requirement, use the following formula:

[0098] Q n-m,电池k,n-m’ >Q 目标 (3)

[0099] If Q n-m,电池k,n-m’ ≤Q 目标 , you need to readjust the system initial flow.

[0100] It should be noted that Q 目标 Refers to the minimum coolant flow rate required for each battery pack to achieve the expected thermal management effect (cooling or heating). The target flow rate is directly related to the thermal load of the equipment. Generally, battery manufacturers or liquid cooling system design goals provide clear flow requirements, and Q can be set directly according to the flow value required by the equipment. 目标 For example, a battery manufacturer provides "10L / min coolant flow rate for each battery pack" as a requirement. 目标 It can also be obtained through the formula, Q 目标 =P 热 / ρ·c·ΔT, where P 热 It represents the heat generated by the battery pack (heat load), in W; ρ represents the coolant density, in kg / m 3 ; c represents the specific heat capacity of the coolant, the unit is J / (kg·K); ΔT represents the inlet and outlet temperature difference of the coolant, the unit is K.

[0101] Step 4: Calculate the actual resistance of each section of the system based on the flow distribution in step 3.

[0102] The purpose of step 4 is to calculate the resistance of each section of the system, identify whether the flow distribution meets expectations, and find possible flow bottleneck sections, optimize system energy consumption, reduce unnecessary resistance losses, and improve the efficiency of coolant circulation. Provide a basis for pipeline adjustment and pump output optimization to ensure that the coolant has reasonable flow resistance while meeting the target flow.

[0103] The segment resistance H of the i-th segment of the system i Determined by the following formula:

[0104]

[0105] in,

[0106] Where: H i represents the resistance of the i-th section, in Pa; v i Indicates the speed of the i-th segment, in m / s; d i Indicates the pipe diameter of the i-th section, in m; l i represents the length of the i-th segment, in m; ρ represents the density of the coolant, in kg / m 3 ; ε i Indicates the resistance coefficient associated with the pipe accessories; Q i represents the flow of the i-th segment (provided by the allocation result of step 3). o (m 2 / s) represents the reference coefficient of equivalent kinematic viscosity relative to ethylene glycol, K o (m) represents the reference coefficient of the equivalent roughness height relative to the plastic pipe, preferably 1; Used to calculate the resistance associated with fluid flow through different pipe accessories; It represents the pipe resistance related to pipe length, flow rate, viscosity parameters and pipe diameter.

[0107] Step 5: Based on the system segmented resistance, determine the total pipe resistance of the complete circulation path from the water pump outlet to the farthest battery pack and then back to the water tank. Determine the total system resistance through the total pipe resistance and equipment resistance. Use the total system resistance to check whether the water pump head meets the system total resistance requirements.

[0108] The purpose of step 5 is to evaluate whether the flow and pressure of the water pump in the entire system can meet the flow requirements of the farthest battery pack, and to determine whether the water pump operating point falls within its optimal efficiency range to ensure efficient operation of the system.

[0109] Step 5 includes:

[0110] Step 5.1: Determine the complete circulation path from the water pump outlet to the farthest battery pack and then back to the water tank. Based on the system segmented resistance obtained in step 4, obtain the total resistance of the pipeline.

[0111] The complete circulation path includes: pump outlet to PTC heater, PTC heater to battery pack inlet, battery pack outlet to heat exchanger, heat exchanger to water tank inlet. According to formula (4), calculate the resistance of each pipe section.

[0112] By adding up all the path resistances, we get the total pipe resistance:

[0113]

[0114] Step 5.2: Obtain the resistance of each device (such as PTC heater, battery pack, heat exchanger, etc.) through the device resistance model in step 2, and combine it with the total pipeline resistance obtained in step 5.1 to obtain the total system resistance:

[0115] H 系统总 =H 管道max +H 设备 (7)

[0116] Step 5.3: If 0<(H 泵 -H 系统总 )<1m H2O, then determine the pump head H 泵 Initially meet H 系统总 According to the requirements, the flow rate Q is determined according to the performance curve of the water pump. 泵 and the pump head H 泵 Is it in the highest efficiency range? If it is within ±10% of the highest efficiency, then the pump head H is determined. 泵 Satisfy H 系统总 If it exceeds this range, return to step 1 to readjust the system initial flow Q 泵 , and repeat the calculation according to steps 1-5 until the system meets the requirements.

[0117] It should be noted that the pump head can be obtained through formulas, pump performance curves or experimental tests. The pump performance curve is provided by the pump manufacturer and can show the pump head performance at different flow rates. According to the target flow rate calculated by the system, the corresponding head H is found on the performance curve. 泵 .

[0118] Step 6: Determine the flow uniformity by calculating the pipe resistance between nodes. If it is uneven, redistribute the flow or optimize the pipeline design until the flow of all battery packs is uniform.

[0119] The purpose of step 6 is to further analyze the flow distribution of each battery pack, determine the flow uniformity based on the resistance data provided in step 5, and achieve more efficient flow distribution through adjustment and optimization. By adjusting the flow distribution, the waste of coolant caused by resistance differences can be reduced, and the cooling efficiency and energy utilization rate can be improved. Ensure that the coolant flow received by each battery pack in the system is close to the same to prevent overcooling or overheating caused by uneven flow distribution. Ensure that the system can maintain the uniformity of battery pack flow distribution under various working conditions to meet different load requirements.

[0120] Step 6 includes:

[0121] Step 6.1: Based on the pipeline resistance of each node obtained in step 4, define the maximum node pipeline resistance and the minimum node pipeline resistance.

[0122] The maximum node pipeline resistance can be expressed as:

[0123] H max =max{H (m-1),…(n-1),电池1,(n-1)’…(m-1)’ , …, H (m-1),…(n-k),电池k,(n-k)’…(m-1)’}

[0124] The minimum node pipeline resistance can be expressed as:

[0125] H min =min{H (m-1),…(n-1),电池1,(n-1)’…(m-1)’ , …, H (m-1),…(n-k),电池k,(n-k)’…(m-1)’}

[0126] Step 6.2: Determine the uniformity of the resistance of each pipeline. If (H max -H min ) / H min >10%, it means that the flow distribution is uneven; otherwise, if the uniformity meets the requirements, there is no need to adjust the flow.

[0127] Step 6.3: If the uniformity of pipeline resistance does not meet the requirements, redistribute the flow Q between node (m-1) and node (m) (m-1),m , otherwise let m=m-1 and determine the next node until m is the minimum number of nodes.

[0128] It should be noted that m=n+1,n,n-1,...3,2, where m is in sequence from the branch node closest to the battery to the system total flow node.

[0129] Redistribute the traffic Q between node (m-1) and node (m) (m-1),m The process includes:

[0130] First, define the branch numbering sequence [(m)-k] of node (m) according to the resistance of each pipeline:

[0131] [H [(m-1)-i],[(m)-1] +H [(m)-1]’,[(m-1)-i]’ ]>[H [(m-1)-i],[(m)-2]+H[(m)-2]’,[(m-1)-i]’ ]>...>[H [(m-1)-i],[(m)-k] +H [(m)-k]’,[(m-1)-i]’ ], where i = 1, 2, 3, ... (m-1) the total number of branches of the node; k = 1, 2, 3, ... (m) the total number of branches of the node;

[0132] Then, according to the resistance distribution of each pipeline, the flow ratio relationship between the node [(m-1)-i] and each node [(m)-k] is obtained:

[0133] Q [(m-1)-i],[(m)-1] :Q [(m-1)-i],[(m)-2] :Q [(m-1)-i],[(m)-3] :..:Q [(m-1)-i],[(m)-k] =[H [(m-1)-i],[(m)-k] +H [(m)-k]’,[(m-1)-i]’] :...[H [(m-1)-i],[(m)-2]+ H [(m)-2]’,[(m-1)-i]’ ]:[H [(m-1)-i],[(m)-1] +H [(m)-1]’,[(m-1)-i]’ ].

[0134] Let m=m-1, and determine the flow ratio of the next node until m is the minimum number of nodes; where m is in order from the branch node closest to the battery to the system total flow node, m=n+1,n,...3,2.

[0135] Furthermore, according to the flow ratio of each node branch, the flow Q is redistributed (m),[(m+1)-i] , i=1,2,3,...a, we get: ...

[0137]

[0138] Let m=m+1, and recalculate the flow of the next node until m is the maximum number of nodes; where m is the branch node from the system total flow node to the closest branch node to the battery in sequence, m=1,2,3,...n-1.

[0139] Step 6.4: If all battery flow rates meet Q 电池1 ≈Q 电池2 ≈…≈Q 电池k , the uniformity target is achieved. If not, optimize the pipeline design and redistribute the flow according to step 6.1.

[0140] The present invention also provides a flow control system for a liquid cooling system of a power battery on an electric vehicle, which is characterized by comprising:

[0141] The parameterization processing module is used to perform parameterization processing on the geometric model of the power battery liquid cooling system.

[0142] The resistance modeling module is used to establish a device resistance model based on the device flow resistance characteristic data of the power battery liquid cooling system.

[0143] The traffic distribution module is used to distribute the initialization system traffic, build a dynamic traffic distribution model based on the traffic relationship between nodes at all levels, calculate the traffic flowing through each level of nodes, and determine whether the traffic reaching the battery meets the target requirements.

[0144] The resistance calculation module is used to calculate the actual resistance of each section of the system based on the flow distribution.

[0145] The total resistance verification module is used to determine the total pipeline resistance of the complete circulation path from the water pump outlet to the farthest battery pack and then back to the water tank based on the system segmented resistance, and to determine the total system resistance through the total resistance and equipment resistance to verify whether the water pump head meets the system total resistance requirements.

[0146] The uniformity judgment module is used to calculate the pipeline resistance between nodes and judge the flow uniformity. If it is uneven, the flow is redistributed or the pipeline design is optimized until the flow of all battery packs is uniform.

[0147] Through the collaboration between the above modules, the system realizes dynamic optimization and uniform distribution of the flow of the electric vehicle's onboard power battery liquid cooling system to meet the battery's target flow requirements and ensure flow uniformity, while optimizing the pipeline design and verifying the matching of system resistance and water pump head.

[0148] The present invention provides a flow control method for an electric vehicle onboard power battery liquid cooling system that does not rely on simulation software. By establishing an equipment resistance model, a dynamic flow distribution model and accurate resistance calculation, combined with water pump head verification and node resistance uniformity judgment, the coolant flow distribution is dynamically optimized to achieve precise flow control of multiple battery packs, improved cooling uniformity and thermal balance capabilities, significantly improve system operating efficiency, stability and economy, extend battery life and support efficient design and operation of the liquid cooling system.

[0149] The above is only an embodiment of the present invention, and the common sense such as the known specific structure and characteristics in the scheme is not described in detail here. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the attached claims rather than the above description, so it is intended to include all changes within the meaning and scope of the equivalent elements of the claims. Any figure mark in the claims should not be regarded as limiting the claims involved.

Claims

1. A flow control method for a liquid cooling system of an electric vehicle power battery, characterized in that: Methods include: Step 1: Parameterize the geometric model of the power battery liquid cooling system; Step 2: Establishing a device resistance model based on the flow resistance characteristic data of the device of the power battery liquid cooling system; Step 3: Allocate the initialization system flow, build a dynamic flow distribution model based on the flow relationship between nodes at all levels, calculate the flow through each level of nodes, and determine whether the flow reaching the battery meets the target requirements. If it meets the target requirements, execute the next step. If it does not meet the target requirements, readjust the initial flow according to step 1; Step 4: Calculate the actual resistance of each section of the system based on the flow distribution in step 3; Step 5: According to the system segmented resistance, determine the total pipe resistance of the complete circulation path from the water pump outlet to the farthest battery pack and then back to the water tank. Determine the total system resistance through the total pipe resistance and equipment resistance. Verify whether the water pump head meets the system total resistance requirements through the system total resistance. Step 6: Determine the flow uniformity by calculating the pipe resistance between nodes. If it is uneven, redistribute the flow or optimize the pipeline design until the flow of all battery packs is uniform.

2. The flow control method for the liquid cooling system of the electric vehicle power battery according to claim 1 is characterized in that: In step 1, the parameters of the geometric model of the power battery liquid cooling system include each shunt node, the equipment inlet flow Q in,k , Equipment export flow Q out,k , Pipeline length l i,j , Pipe diameter d i,j 、Pipeline accessories resistance coefficient ε i,j and the preset initialization system flow Q 泵 .

3. The flow control method for the liquid cooling system of the electric vehicle power battery according to claim 1 is characterized in that: In step 1, the coolant outlet of the PTC heater of the power battery liquid cooling system is node 1. Starting from node 1, the coolant is diverted to different branches of node 2. Starting from each branch of node 2, the coolant is further diverted to different branches of node 3. Starting from each branch of node 3, the coolant is further diverted to different branches of the next node until each battery pack receives the coolant input from the corresponding node for heat exchange. After the coolant completes the heat exchange in the battery pack, it is gradually returned to the upper-level node through the reflux path, and finally the coolant returns to the water tank.

4. The flow control method for a liquid cooling system of an electric vehicle power battery according to claim 1, characterized in that: In step 2, the equipment resistance model is determined by the following formula: H 设备 =aQ m +bQ m-1 +cQ m-2 +……+Q+k Where: H 设备 Indicates equipment resistance, unit is Pa; Q indicates flow rate, unit is m 3 / s; m represents the number of fitting times; parameters a, b, c, ... k represent the fitting coefficients.

5. The flow control method for the liquid cooling system of the electric vehicle power battery according to claim 1 is characterized in that: Step 3 includes: Step 3.1: Build a dynamic traffic distribution model to define the traffic between nodes; Step 3.2: Based on step 3.1, determine whether the battery flow rate reaches the target flow rate requirement. If it does, proceed to the next step to calculate the system segmented resistance. Otherwise, return to step 1 to reinitialize the system flow rate Q. 泵 .

6. The flow control method for the liquid cooling system of the electric vehicle power battery according to claim 5 is characterized in that: In step 3.1, the dynamic traffic distribution model is determined by the following formula: Q 换热器,泵 =Q 泵,PTC =Q PTC,1 =a×Q 1,2-1 =a×Q 1,2-2 =……=a×Q 1,2-a =ab× Q 2-1,3-1 =ab×Q 2-1,3-2 =……=ab×Q 2-1,3-b =abc×Q 3-1,4-1 =abc×Q 3-1,4-2 =……=abc×Q 3-1,4-c =(abc……n)×Q n-m,电池k,n-m’ ; Where: Q 换热器,泵 Indicates the flow rate from the heat exchanger to the pump; Q 泵,PTC Indicates the flow rate from the pump to the PTC; Q PTC,1 Indicates the traffic from PTC to node 1; Q 1,2-1 , Q 1,2-2 , Q 1,2-a They represent the flow of each branch node from node 1 to node 2; Q 2-1,3-1 , Q 2-1,3-2 、ab×Q 2-1,3-b They represent the flow from one of the branch nodes in node 2 to each branch node in node 3; Q 3-1,4-1 , Q 3-1,4-2 , Q 3-1,4-c They represent the flow from one of the branch nodes in node 3 to each branch node in node 4; Q n-m,电池k,n-m’ Indicates the flow with the kth battery; the flow of each node multiplied by a, b, c...n means that the flow will be multiplied by the diversion ratio coefficient in turn when passing through each level of nodes; In step 3.2, it is determined whether the battery flow rate reaches the target flow rate requirement according to the following formula: Q n-m,电池k,n-m’ >Q 目标 If Q n-m,电池k,n-m’ ≤Q 目标 , you need to readjust the system initial flow.

7. The flow control method for a liquid cooling system of a power battery on an electric vehicle according to claim 1, characterized in that: In step 4, the segment resistance H of the i-th segment of the system i Determined by the following formula: in, Where: H i represents the resistance of the i-th section, in Pa; v i Indicates the speed of the i-th segment, in m / s; d i Indicates the pipe diameter of the i-th section, in m; l i represents the length of the i-th segment, in m; ρ represents the density of the coolant, in kg / m 3 ; ε i Indicates the resistance coefficient associated with the pipe accessories; Q i Indicates the flow rate of the i-th section, in m 3 / s.v o (m 2 / s) represents the reference coefficient of equivalent kinematic viscosity relative to ethylene glycol, K o (m) represents the reference coefficient of the equivalent roughness height relative to the plastic pipe, which is preferably 1.

8. The flow control method for a liquid cooling system of a power battery on an electric vehicle according to claim 1, characterized in that: Step 5 includes: Step 5.1: Determine the complete circulation path from the water pump outlet to the farthest battery pack and then back to the water tank. Based on the system segmented resistance obtained in step 4, obtain the total resistance of the pipeline; Step 5.2: Obtain the resistance of each device through the device resistance model in step 2, and combine it with the total pipeline resistance obtained in step 5.1 to obtain the total system resistance; Step 5.3: If 0<(H 泵 -H 系统总 )<1m H2O, then determine the pump head H 泵 Initially meet H 系统总 According to the requirements, the flow rate Q is determined according to the performance curve of the water pump. 泵 and the pump head H 泵 Is it in the highest efficiency range? If it is within ±10% of the highest efficiency, then the pump head H is determined. 泵 Satisfy H 系统总 If it exceeds this range, return to step 1 to readjust the system initial flow Q 泵 , and repeat the calculation according to steps 1-5 until the system meets the requirements.

9. The flow control method for a liquid cooling system of a power battery on an electric vehicle according to claim 1, characterized in that: Step 6 includes: Step 6.1: Based on the pipeline resistance of each node obtained in step 4, define the maximum node pipeline resistance H max and the minimum node pipe resistance H min ; Step 6.2: Determine the uniformity of the resistance of each pipeline. If (H max -H min ) / H min >10%, it means that the flow distribution is uneven, otherwise, if the uniformity meets the requirements, there is no need to adjust the flow; Step 6.3: If the uniformity of pipeline resistance does not meet the requirements, redistribute the flow Q between node (m-1) and node (m) (m-1),m , otherwise let m = m-1 and determine the next node until m is the minimum number of nodes; Step 6.4: If all battery flow rates meet Q 电池1 ≈Q 电池2 ≈…≈Q 电池k , the uniformity target is achieved. If not, optimize the pipeline design and redistribute the flow according to step 6.

1.

10. A flow control system for a liquid cooling system of a power battery on an electric vehicle, characterized in that: include: A parameterized processing module, used for parameterizing the geometric model of the power battery liquid cooling system; Resistance modeling module, used to establish equipment resistance model based on equipment flow resistance characteristic data of power battery liquid cooling system; The flow distribution module is used to distribute the initialization system flow, build a dynamic flow distribution model based on the flow relationship between nodes at all levels, calculate the flow through each level of nodes, and determine whether the flow reaching the battery meets the target requirements; Resistance calculation module, used to calculate the actual resistance of each section of the system based on flow distribution; The total resistance verification module is used to determine the total resistance of the pipeline in the complete circulation path from the water pump outlet to the farthest battery pack and then back to the water tank according to the system segment resistance, and determine the total system resistance through the total resistance and equipment resistance to verify whether the water pump head meets the system total resistance requirements; The uniformity judgment module is used to calculate the pipeline resistance between nodes and judge the flow uniformity. If it is uneven, the flow is redistributed or the pipeline design is optimized until the flow of all battery packs is uniform.

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