Method and system for improving thermal management performance of fast charging battery

Abstract

The invention provides a method and system for improving the thermal management performance of a fast charging battery, and belongs to the technical field of battery management. Comprising the following steps: S1, configuring a liquid cooling plate at one end of a battery pack, arranging a plurality of battery cells on the end surface of the liquid cooling plate at intervals along the length extension direction of the liquid cooling plate, and arranging a heat-absorbing porous material on the end surface of the width extension direction of the plurality of battery cells, the heat-absorbing porous material being used for absorbing heat of the battery cells; s2, acquiring the temperature of a plurality of battery cells, the water inlet and outlet temperature difference of the liquid cooling plate and the charging current in real time; the execution module is electrically connected with the flexible circuit, and provides input voltage for the heat absorption porous material through the flexible circuit; the method comprises the following steps: acquiring a temperature curve of a battery cell in a charging process, and estimating the heat dissipation performance of a heat-absorbing porous material; and S3, evaluating the deviation between the actual temperature and the theoretical temperature of the surfaces of the plurality of battery cells under the current charging condition and the heat dissipation performance, providing an input voltage signal for the flexible circuit, and adjusting the porosity of the heat absorption porous material.

Description

Technical Field

[0001] The present invention relates to the field of battery balancing technology, and in particular to a method and system for improving the thermal management performance of a fast-charging battery. Background Art

[0002] With the intensive release of 800V high-voltage fast-charging models for new energy vehicles, leading automakers are accelerating their deployment in the new energy charging field, especially in the construction of high-power supercharging piles, to meet the demand for rapid energy replenishment. Currently, for most power batteries on the market, improving fast-charging technology will have the following impacts: 1. The fast-charging capability of individual cells needs to be improved: To meet the time requirements for fast charging, the cells need to meet 2C or even 3C fast-charging capabilities. As the fast-charging capability increases, the DC internal resistance (DCR) of the cells will increase; 2. The current-carrying capacity of electrical components needs to be improved; the following problems are very likely to occur: 1. Fast-charging time does not meet the expected target: During fast charging, the battery temperature rises rapidly, the battery maximum temperature changes rapidly, and the high-temperature charging area is reached in the charging MAP. The fast-charging rate of the cell decreases, resulting in an increase in battery charging time; 2. Thermal management performance decreases: The DCR of high-fast-charging-rate cells increases, and the fast-charging current increases, resulting in increased heat generation during fast charging. When the boundary conditions of the vehicle's thermal management system remain unchanged (taking liquid cooling as an example, the water flow rate remains unchanged and the liquid cooling plate remains unchanged), it is difficult to meet the heat dissipation requirements of the battery cells, resulting in a serious decline in the battery's thermal management performance.

[0003] Therefore, it is very necessary to provide a method and system for improving the thermal management performance of fast-charging batteries, improve the thermal management performance of batteries under the boundary conditions of the original vehicle thermal management, better adapt to the fast charging requirements of large currents, and improve the stability and safety of fast charging. Summary of the Invention

[0004] In view of this, the present invention proposes a method and system that can improve the local heat exchange capacity of the battery cell and enhance the thermal management performance of the fast-charging battery without changing the overall spatial layout of the existing battery pack.

[0005] In one aspect, the present invention provides a method for improving the thermal management performance of a fast-charging battery, comprising the following steps:

[0006] S1: A liquid cooling plate is disposed at one end of the battery pack, and a plurality of battery cells are disposed on an end surface of the liquid cooling plate. The plurality of battery cells are spaced apart along the length of the liquid cooling plate, and a heat-absorbing porous material is disposed on the end surfaces of the plurality of battery cells in the width direction. The heat-absorbing porous material is used to absorb heat from the battery cells.

[0007] S2: Real-time acquisition of the temperature of several battery cells, the temperature difference between the inlet and outlet water of the liquid cooling plate, and the charging current; the execution module is electrically connected to the flexible circuit, and an input voltage is provided to the heat-absorbing porous material through the flexible circuit; the temperature curve of the battery cells during the charging process is acquired, and the heat dissipation performance of the heat-absorbing porous material is estimated;

[0008] S3: Evaluate the deviation between the actual and theoretical temperatures of several battery cell surfaces under current charging conditions and heat dissipation performance, provide input voltage signals to the flexible circuit, and adjust the porosity of the heat-absorbing porous material.

[0009] Based on the above technical solution, preferably, the heat dissipation performance of the heat-absorbing porous material is estimated in step S2, which is a dynamic equation of the temperature change of the heat-absorbing porous material over time: where Q gen is the heat generation rate of the battery cell, α is the proportional coefficient; λ eff is the thermal conductivity, is the gradient operator, is the temperature gradient, ρ is the density of the heat-absorbing porous material, C p is the specific heat capacity of the heat-absorbing porous material, T is the temperature of the heat-absorbing porous material, represents the rate of change of internal energy per unit volume of heat-absorbing porous material, represents the surface energy change rate of the heat-absorbing porous material per unit time, γ is the surface tension, and A is the specific surface area; the dynamic equation is solved to obtain the change of the temperature of the heat-absorbing porous material with time, and the temperature-time curve of the heat-absorbing porous material during charging is obtained.

[0010] Preferably, the cell heat generation rate Q gen Satisfies the following heat balance model: Q gen =Q liquid +Q solid where Q liquid The heat dissipation shared by the liquid cooling plate, Q liquid =h liquid ·A bottom ·(T cell -T B ), h liquid is the heat transfer coefficient between the battery cell and the liquid cooling plate, A bottom is the total contact area between the bottom surface of several battery cells and the liquid cooling plate, T cell is the average temperature of the battery cell, T B Q is the water outlet temperature of the liquid cooling plate; solid The heat dissipation shared by the heat-absorbing porous material, Q solid =h solid ·A side ·(T cell -T ambi ), hsolid is the heat transfer coefficient between the battery cell and the heat-absorbing porous material, A side is the total contact area between the side surfaces of several battery cells and the heat-absorbing porous material, T ambi is the ambient temperature; then the proportionality coefficient

[0011] More preferably, the volume of the heat-absorbing porous material is V, and the heat-absorbing porous material includes a plurality of spherical solid matrices and air in the pores; the porosity of the heat-absorbing porous material is φ, and the volume of the plurality of spherical solid matrices is V solid , V solid =(1-φ)V; let the volume of a single spherical solid matrix be The surface area of a single spherical solid matrix is S sphere =πd 2 , then the specific surface area of the heat-absorbing porous material is

[0012] More preferably, the relationship between the porosity of the heat-absorbing porous material and the input voltage of the heat-absorbing porous material is: φ=φ0+δ·D m ·V i n ·r p , φ0 is the initial porosity value of the heat-absorbing porous material; δ is the correction coefficient, δ∈(0,1); D is the duty cycle of the input voltage, D∈[0,100%]; V i is the amplitude of the input voltage, dimensionless; r is the equivalent resistance of the heat-absorbing porous material, dimensionless; m, n, p are fitting parameters, m∈(0,1), n∈(0,2), p∈(-1,1).

[0013] Further preferably, in step S3, evaluating the deviation between the actual surface temperature and the theoretical temperature of the plurality of battery cells under the current charging conditions and heat dissipation performance is performed by the control unit obtaining a preset temperature-time curve of the battery cell during charging from the charging MAP, and judging, according to the temperature-time curve of the heat-absorbing porous material during charging, a deviation change trend between the temperature value on the preset temperature-time curve of the battery cell during charging and the temperature value of the corresponding temperature-time curve of the heat-absorbing porous material during charging.

[0014] Further preferably, the step of providing an input voltage signal to the flexible circuit to adjust the porosity of the heat-absorbing porous material in step S3 is to change the input voltage provided by the flexible circuit to adjust the porosity of the heat-absorbing porous material when any one of the following conditions is met:

[0015] 1) The temperature difference between different battery cell surfaces, or the temperature difference between different surfaces of the same battery cell, reaches 5°C or more;

[0016] 2) The maximum surface temperature of any battery cell reaches 50°C or above;

[0017] 3) The water outlet temperature T of the liquid cooling plate B Reach more than 95% of the set upper limit of water outlet temperature;

[0018] 4) Under the same number of cycles, the temperature difference corresponding to several consecutive sampling points of the preset temperature-time curve of the battery cell and the temperature-time curve of the heat-absorbing porous material during charging under the same charging conditions shows an increasing trend, and the temperature difference exceeds 10% of the temperature value on the preset temperature-time curve of the battery cell.

[0019] On the basis of the above technical solutions, preferably, the heat-absorbing porous material is a carbon-based porous material, a porous metal foam material, or a composite structure of a porous metal foam material and a phase change material.

[0020] On the other hand, the present invention also provides a system for improving the thermal management performance of a fast-charging battery, which is used to implement the above-mentioned method for improving the thermal management performance of a fast-charging battery, including:

[0021] A liquid cooling plate is provided at one end of the battery pack;

[0022] A plurality of battery cells are arranged on the end surface of the liquid cooling plate, the plurality of battery cells are arranged at intervals along the length extension direction of the liquid cooling plate, and the end surfaces of the plurality of battery cells in the width extension direction are provided with a heat-absorbing porous material, the heat-absorbing porous material is used to absorb heat from the battery cells;

[0023] a flexible circuit disposed on a surface of the heat-absorbing porous material;

[0024] The monitoring module is set on the surface of several battery cells and the water inlet and outlet of the liquid cooling plate to obtain the real-time battery cell temperature, the temperature difference between the inlet and outlet water of the liquid cooling plate, and the charging current;

[0025] The execution module is electrically connected to the flexible circuit, and provides an input voltage to the heat-absorbing porous material through the flexible circuit, thereby changing the porosity of the heat-absorbing porous material and converting the heat on the surface of the battery cell into the surface energy of the heat-absorbing porous material;

[0026] The control module is electrically connected to the monitoring module and the flexible circuit. The control module obtains the heat generated by the battery cell during charging and the theoretical fast charging time. It also obtains the input voltage of the heat-absorbing porous material and estimates the heat dissipation performance of the heat-absorbing porous material.

[0027] The control unit evaluates the deviation between the actual temperature and the theoretical temperature under the current charging conditions and heat dissipation performance, and selectively adjusts the input voltage of the execution module.

[0028] Based on the above technical solution, preferably, the monitoring module includes an NTC temperature sensor, a water temperature sensor and a clock circuit. The NTC temperature sensor is arranged on the surface of several batteries to obtain the maximum temperature of the battery cell surface; the water temperature sensor is arranged at the water outlet of the liquid cooling plate to obtain the water outlet temperature of the liquid cooling plate; the clock circuit is used to obtain real-time time.

[0029] The present invention provides a method and system for improving the thermal management performance of fast-charging batteries, which have the following advantages over the prior art:

[0030] (1) The present invention uses a flexible circuit to adjust the porosity of the heat-absorbing porous material in real time, optimize the specific surface area, and significantly enhance the heat dissipation capacity. By combining data such as the battery cell temperature, the water outlet temperature of the liquid cooling plate, and the charging current, the heat dissipation requirements are dynamically matched to avoid local overheating of the battery cell or uncontrolled temperature rise of the battery pack as a whole.

[0031] (2) The liquid cooling plate is responsible for heat dissipation from the bottom of the battery cell, and the heat-absorbing porous material is responsible for lateral heat transfer of the battery cell, thereby covering the heat conduction path of the battery cell in multiple dimensions. By improving the porosity, local aging is avoided and the cycle life of the battery is extended;

[0032] (3) By introducing the dynamic equation of the temperature change of heat-absorbing porous materials over time, the heat generation model of the battery cell, and the relationship between porosity and heat dissipation, the heat dissipation performance of the heat-absorbing porous materials is accurately estimated, achieving accurate and reliable global thermal management. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 This is a flow chart of a method and system for improving thermal management performance of a fast-charging battery according to the present invention;

[0035] Figure 2 This is a structural block diagram of the monitoring module, control module and execution module of a method and system for improving the thermal management performance of a fast-charging battery according to the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] In one embodiment, Figure 1 As shown, the present invention provides a method for improving the thermal management performance of a fast-charging battery, comprising the following steps:

[0038] S1: A liquid cooling plate is disposed at one end of the battery pack, and a plurality of battery cells are arranged on the end surface of the liquid cooling plate. The plurality of battery cells are arranged at intervals along the length extension direction of the liquid cooling plate, and a heat-absorbing porous material is provided on the end surface of the plurality of battery cells in the width extension direction. The heat-absorbing porous material is used to absorb heat from the battery cells.

[0039] The battery pack box is a hollow rectangular structure. In order to increase the energy density and load as many battery cells as possible, the liquid cooling plate is not placed between adjacent battery cells, but on the bottom of the battery cells. Adhesive or buffer materials are filled between adjacent battery cells to achieve a tight layout of the battery cells. However, since large-surface water cooling is not adopted and the contact area between each battery cell and the liquid cooling plate is limited, this application proposes a solution of setting a heat-absorbing porous material on the side of the battery cell to assist in heat conduction.

[0040] In one embodiment, the heat-absorbing porous material is a carbon-based porous material, a porous metal foam material, or a composite structure of a porous metal foam material and a phase change material. For phase change materials, a PWM signal of a certain intensity can cause the structure of the porous material to change, thereby changing the pore size. Phase change materials undergo phase transitions when the temperature changes. If the pore size can be precisely controlled by PWM signals according to factors such as temperature, a more suitable spatial environment can be provided for the phase change material. Carbon-based porous materials have a high specific surface area and a rich pore structure. Porous materials controlled by PWM signals can be combined with carbon-based porous materials to affect the distribution and connectivity of their internal pores by changing the external pore environment.

[0041] Changing the porosity occurs when the material's heat dissipation reaches a certain level. Because the battery pack itself is a sealed environment, the material absorbs heat and then radiates it. When the temperature inside the battery pack reaches a certain level, the material's heat dissipation by radiation cannot further reduce the temperature of the battery cell itself. The purpose of changing the porosity is to convert the heat on the battery cell surface into material surface energy. The surface energy of an object is usually related to factors such as the state and roughness of the surface. When the porosity of a material is changed, the specific surface area of the material changes. Generally speaking, as the porosity increases, the specific surface area increases, exposing more of the material's internal surface, which increases the material's surface energy. According to the law of conservation of energy, the increased surface energy of the material must come from other forms of energy, which may include energy originally present on the surface of the object.

[0042] For example, when an electric field exceeding the threshold is applied (such as a PWM signal of 100Hz and 50% duty cycle), the molecular chains on the surface of the nanopores are rearranged, resulting in a change in the equivalent pore size. For example, the pore size of PET nanopores can be expanded from 50nm to 70nm under an electric field of 10V / cm, and the process is reversible. An alternating electric field (such as 200Hz PWM) can rearrange nanoparticles through dielectrophoretic force, thereby changing the porosity of the material. In TiO2 nanomaterials, the porosity is increased from 35% to 50%, and the pore distribution is more uniform. Within the normal operating temperature range of the battery, the effects of Joule heat and chemical heat generation on the porosity of nanomaterials are negligible (<1%), while the PWM electric signal can significantly change the porosity (10-15%) through the electric field effect.

[0043] By modifying the porosity of some metal foams, their specific surface area can be increased several times, or even dozens of times, compared to the original dense metal. This modified porosity allows for greater heat dissipation through conduction and convection over a larger area, improving heat dissipation.

[0044] S2: Real-time acquisition of the temperature of several battery cells, the temperature difference between the inlet and outlet water of the liquid cooling plate, and the charging current; the execution module is electrically connected to the flexible circuit, and an input voltage is provided to the heat-absorbing porous material through the flexible circuit; the temperature curve of the battery cell during the charging process is acquired, and the heat dissipation performance of the heat-absorbing porous material is estimated.

[0045] The heat dissipation performance of the heat-absorbing porous material is estimated in step S2, which is a dynamic equation of the temperature change of the heat-absorbing porous material over time: where Q gen is the heat generation rate of the battery cell, α is the proportional coefficient; λ eff is the thermal conductivity, is the gradient operator, is the temperature gradient, ρ is the density of the heat-absorbing porous material, C p is the specific heat capacity of the heat-absorbing porous material, T is the temperature of the heat-absorbing porous material, represents the rate of change of internal energy per unit volume of heat-absorbing porous material, represents the rate of change of the surface energy of the heat-absorbing porous material per unit time, γ is the surface tension, and A is the specific surface area; solving the dynamic equation yields the change in the temperature of the heat-absorbing porous material over time, and thus the temperature-time curve of the heat-absorbing porous material during charging. The dynamic equation can be numerically solved using software such as MATLAB, COMSOL Multiphysics, or ANSYS, with initial conditions set, such as setting the initial temperature of the heat-absorbing porous material to the ambient temperature. Solving partial differential equations using the aforementioned software is a common technique in the art and will not be elaborated upon here.

[0046] In one embodiment, the cell heat generation rate Q gen Satisfies the following heat balance model: Q gen =Q liquid +Q solid , where Q liquid The heat dissipation shared by the liquid cooling plate, Q liquid =h liquid ·A bottom ·(T cell -T B ), h liquid is the heat transfer coefficient between the battery cell and the liquid cooling plate, A bottom is the total contact area between the bottom surface of several battery cells and the liquid cooling plate, T cell is the average temperature of the battery cell, T B Q is the water outlet temperature of the liquid cooling plate; solid The heat dissipation shared by the heat-absorbing porous material, Q solid =h solid ·A side ·(T cell -T ambi ), h solid is the heat transfer coefficient between the battery cell and the heat-absorbing porous material, A side is the total contact area between the side surfaces of several battery cells and the heat-absorbing porous material, T ambi is the ambient temperature; then the proportionality coefficient The heat balance model shows that when the cell temperature is stable, the heat generated by Joule heat and chemical reaction heat inside the cell is balanced and matched with the heat exchange capacity of the liquid cold plate and the heat-absorbing porous material. Within the processing capacity of the heat-absorbing porous material, the heat dissipation shared by the heat-absorbing porous material will follow the cell heat generation rate Q gen When the heat dissipation of the current heat-absorbing porous material does not meet the demand, the heat dissipation of the heat-absorbing porous material can be dynamically adjusted by adjusting the porosity within the performance range of the heat-absorbing porous material to meet the shortcomings of the liquid cooling plate heat exchange efficiency limited by high-current fast charging and close layout of battery cells.

[0047] In one embodiment, the heat-absorbing porous material is calculated as follows: let the volume of the heat-absorbing porous material be V, and the heat-absorbing porous material includes a plurality of spherical solid matrices and air in the pores; let the porosity of the heat-absorbing porous material be φ, and the volume of the plurality of spherical solid matrices be V solid , V solid =(1-φ)V; let the volume of a single spherical solid matrix be The surface area of a single spherical solid matrix is S phere =πd 2 , then the specific surface area of the heat-absorbing porous material is

[0048] The relationship between the porosity of the heat-absorbing porous material and the input voltage of the heat-absorbing porous material is: φ=φ0+δ·D m ·V i n ·r p ,φ 0 is the initial porosity value of the heat-absorbing porous material; δ is the correction coefficient, δ∈(0,1); D is the duty cycle of the input voltage, D∈[0,100%]; V i is the amplitude of the input voltage, dimensionless; r is the equivalent resistance of the heat-absorbing porous material, dimensionless; m, n, p are fitting parameters, m∈(0,1), n∈(0,2), p∈(-1,1). It can be seen that within the performance range of the heat-absorbing porous material, the porosity of the heat-absorbing porous material can be changed by changing the amplitude of the input voltage or the duty cycle. The change in porosity will affect the specific surface area A of the heat-absorbing porous material and the surface energy change rate of the heat-absorbing porous material. This changes the internal energy change rate and surface energy state of the heat-absorbing porous material per unit volume, achieving the effect of fine-tuning the heat exchange capacity under high-current charging conditions.

[0049] S3: Evaluate the deviation between the actual and theoretical temperatures of several battery cell surfaces under current charging conditions and heat dissipation performance, provide input voltage signals to the flexible circuit, and adjust the porosity of the heat-absorbing porous material.

[0050] Among them, to evaluate the deviation between the actual temperature and the theoretical temperature of several battery cell surfaces under the current charging conditions and heat dissipation performance, the control unit obtains the preset temperature-time curve of the battery cell during charging from the charging MAP, and judges the deviation change trend of the temperature value on the preset temperature-time curve of the battery cell during charging and the temperature value of the corresponding temperature-time curve of the heat-absorbing porous material during charging according to the temperature-time curve of the heat-absorbing porous material during charging. For a battery pack with a certain cumulative number of cycles, a preset temperature-time curve contains battery cell temperature data corresponding to different charging times. Through the aforementioned solution, the dynamic equation is solved to obtain the change in the temperature of the heat-absorbing porous material over time, and the temperature-time curve of the heat-absorbing porous material during charging is obtained. The actual battery cell temperature corresponding to the corresponding charging time can also be obtained to form a set of corresponding data. In the same charging stage, such as the pre-charging stage, the constant current charging stage, the constant voltage charging stage, and the trickle charging stage, under ideal circumstances, the preset temperature-time curve and the temperature-time curve of the heat-absorbing porous material during charging should have a certain correspondence. That is, when the liquid cooling plate is fully operating, according to the proportional coefficient α, the preset temperature-time curve and the temperature-time curve of the heat-absorbing porous material during charging have a certain similarity and proportional relationship. If the proportional relationship changes significantly, it indicates that the heat dissipation capacity of the heat-absorbing porous material in the current state may be less than ideal.

[0051] The step S3 of providing an input voltage signal to the flexible circuit to adjust the porosity of the heat-absorbing porous material is to change the input voltage provided by the flexible circuit to adjust the porosity of the heat-absorbing porous material when any one of the following conditions is met:

[0052] 1) The temperature difference between different battery cell surfaces, or the temperature difference between different surfaces of the same battery cell, reaches 5°C or more; this situation indicates that the temperature of one or more battery cells is uneven.

[0053] 2) The maximum surface temperature of any battery cell reaches 50°C or above; by limiting the maximum temperature, it is determined that heat dissipation must be immediately enhanced, otherwise there may be a risk of thermal runaway.

[0054] 3) The water outlet temperature T of the liquid cooling plate B The outlet water temperature reaches more than 95% of the upper limit of the setting; this situation indicates that the heat exchange capacity of the liquid cooling plate has basically reached the upper limit.

[0055] 4) Under the same number of cycles, the temperature difference between the preset temperature-time curve of the battery cell and the temperature-time curve of the endothermic porous material during charging at several consecutive sampling points under the same charging conditions shows an increasing trend, and the temperature difference exceeds 10% of the temperature value on the preset temperature-time curve of the battery cell. This indicates that the temperature difference between the current endothermic porous material and the surface temperature of the battery cell during charging is increasing, and it is necessary to change the porosity.

[0056] After adjusting the porosity of the heat-absorbing porous material, if the following conditions are met, it is determined that the current porosity is maintained unchanged:

[0057] A. The difference between the actual temperature and the theoretical temperature tends to stabilize or decrease, and the difference is less than the preset threshold, that is, the temperature difference is less than 10% of the temperature value on the preset temperature-time curve of the battery cell;

[0058] B. The temperature difference between different battery cell surfaces or the temperature difference between different surfaces of the same battery cell shall not exceed 5°C;

[0059] C. The maximum surface temperature of any battery cell is less than 50°C.

[0060] If any of conditions 1)-4) still exists, the amplitude or duty cycle of the input voltage provided by the flexible circuit is further adjusted until any of situations A, B, and C is reached, or the upper limit of the amplitude or duty cycle of the input voltage is reached, and a warning message is issued.

[0061] In addition, if Figure 2 As shown, the present invention also provides a system for improving the thermal management performance of a fast-charging battery, which is used to implement the above-mentioned method for improving the thermal management performance of a fast-charging battery, including:

[0062] A liquid cooling plate is provided at one end of the battery pack;

[0063] A plurality of battery cells are arranged on the end surface of the liquid cooling plate, the plurality of battery cells are arranged at intervals along the length extension direction of the liquid cooling plate, and the end surfaces of the plurality of battery cells in the width extension direction are provided with a heat-absorbing porous material, the heat-absorbing porous material is used to absorb heat from the battery cells;

[0064] a flexible circuit disposed on a surface of the heat-absorbing porous material;

[0065] The monitoring module is set on the surface of several battery cells and the water inlet and outlet of the liquid cooling plate to obtain the real-time battery cell temperature, the temperature difference between the inlet and outlet water of the liquid cooling plate, and the charging current;

[0066] The execution module is electrically connected to the flexible circuit, and provides an input voltage to the heat-absorbing porous material through the flexible circuit, thereby changing the porosity of the heat-absorbing porous material and converting the heat on the surface of the battery cell into the surface energy of the heat-absorbing porous material;

[0067] The control module is electrically connected to the monitoring module and the flexible circuit. The control module integrates a control strategy to obtain the heat generated by the battery cell during charging and the theoretical fast charging time, and to obtain the input voltage of the heat-absorbing porous material and estimate the heat dissipation performance of the heat-absorbing porous material.

[0068] The control unit evaluates the deviation between the actual temperature and the theoretical temperature under the current charging conditions and heat dissipation performance, and selectively adjusts the input voltage of the execution module.

[0069] Among them, the monitoring module includes an NTC temperature sensor, a water temperature sensor and a clock circuit. The NTC temperature sensor is set on the surface of several batteries to obtain the maximum temperature of the battery cell surface; the water temperature sensor is set at the water outlet of the liquid cooling plate to obtain the water outlet temperature of the liquid cooling plate; the clock circuit RTC is used to obtain real-time time.

[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for improving the thermal management performance of a fast-charging battery, characterized in that: The steps include: S1: A liquid cooling plate is disposed at one end of the battery pack, and a plurality of battery cells are disposed on an end surface of the liquid cooling plate. The plurality of battery cells are spaced apart along the length of the liquid cooling plate, and a heat-absorbing porous material is disposed on the end surfaces of the plurality of battery cells in the width direction. The heat-absorbing porous material is used to absorb heat from the battery cells. S2: Real-time acquisition of the temperature of several battery cells, the temperature difference between the inlet and outlet water of the liquid cooling plate, and the charging current; the execution module is electrically connected to the flexible circuit, and an input voltage is provided to the heat-absorbing porous material through the flexible circuit; the temperature curve of the battery cells during the charging process is acquired, and the heat dissipation performance of the heat-absorbing porous material is estimated; S3: Evaluate the deviation between the actual and theoretical temperatures of several battery cell surfaces under current charging conditions and heat dissipation performance, provide input voltage signals to the flexible circuit, and adjust the porosity of the heat-absorbing porous material.

2. The method for improving the thermal management performance of a fast-charging battery according to claim 1, characterized in that: The heat dissipation performance of the heat-absorbing porous material is estimated in step S2, which is a dynamic equation of the temperature change of the heat-absorbing porous material over time: where Q gen is the heat generation rate of the battery cell, α is the proportional coefficient; λ eff is the thermal conductivity, is the gradient operator, is the temperature gradient, ρ is the density of the heat-absorbing porous material, C p is the specific heat capacity of the heat-absorbing porous material, T is the temperature of the heat-absorbing porous material, represents the rate of change of internal energy per unit volume of heat-absorbing porous material, represents the surface energy change rate of the heat-absorbing porous material per unit time, γ is the surface tension, and A is the specific surface area; the dynamic equation is solved to obtain the change of the temperature of the heat-absorbing porous material with time, and the temperature-time curve of the heat-absorbing porous material during charging is obtained.

3. The method for improving the thermal management performance of a fast-charging battery according to claim 2, characterized in that: Cell heat generation rate Q gen Satisfies the following heat balance model: Q gen =Q liquid +Q solid , where Q liquid The heat dissipation shared by the liquid cooling plate, Q liquid =h liquid ·A bottom ·(T cell -T B ), h liquid is the heat transfer coefficient between the battery cell and the liquid cooling plate, A bottom is the total contact area between the bottom surface of several battery cells and the liquid cooling plate, T cell is the average temperature of the battery cell, T B Q is the water outlet temperature of the liquid cooling plate; solid The heat dissipation shared by the heat-absorbing porous material, Q solid =h solid ·A side ·(T cell -T ambi ), h solid is the heat transfer coefficient between the battery cell and the heat-absorbing porous material, A side is the total contact area between the side surfaces of several battery cells and the heat-absorbing porous material, T ambi is the ambient temperature; then the proportionality coefficient 4. The method for improving the thermal management performance of a fast-charging battery according to claim 2, characterized in that: Let the volume of the heat-absorbing porous material be V, which includes several spherical solid matrices and air in the pores; let the porosity of the heat-absorbing porous material be φ, and the volume of the several spherical solid matrices be V solid , V solid =(1-φ)V; let the volume of a single spherical solid matrix be The surface area of a single spherical solid matrix is S sphere =πd 2 , then the specific surface area of the heat-absorbing porous material is 5. The method for improving the thermal management performance of a fast-charging battery according to claim 4, characterized in that: The relationship between the porosity of the heat-absorbing porous material and the input voltage of the heat-absorbing porous material is: φ0 is the initial porosity of the heat-absorbing porous material; δ is the correction coefficient, δ∈(0,1); D is the duty cycle of the input voltage, D∈[0,100%]; V i is the amplitude of the input voltage, dimensionless; r is the equivalent resistance of the heat-absorbing porous material, dimensionless; m, n, and p are fitting parameters, m∈(0, 1), n∈(0, 2), and p∈(-1, 1).

6. The method for improving the thermal management performance of a fast-charging battery according to claim 5, characterized in that: The evaluation of the deviation between the actual surface temperature and the theoretical temperature of the plurality of battery cells under the current charging conditions and heat dissipation performance described in step S3 is that the control unit obtains a preset temperature-time curve of the battery cell during charging from the charging MAP, and determines, based on the temperature-time curve of the heat-absorbing porous material during charging, a deviation trend between the temperature value on the preset temperature-time curve of the battery cell during charging and the temperature value of the corresponding temperature-time curve of the heat-absorbing porous material during charging.

7. The method for improving thermal management performance of a fast-charging battery according to claim 6, characterized in that: The step S3 of providing an input voltage signal to the flexible circuit to adjust the porosity of the heat-absorbing porous material is to change the input voltage provided by the flexible circuit to adjust the porosity of the heat-absorbing porous material when any one of the following conditions is met: 1) The temperature difference between different battery cell surfaces, or the temperature difference between different surfaces of the same battery cell, reaches 5°C or more; 2) The maximum surface temperature of any battery cell reaches 50°C or above; 3) The water outlet temperature T of the liquid cooling plate B Reach more than 95% of the set upper limit of water outlet temperature; 4) Under the same number of cycles, the temperature difference corresponding to several consecutive sampling points of the preset temperature-time curve of the battery cell and the temperature-time curve of the heat-absorbing porous material during charging under the same charging conditions shows an increasing trend, and the temperature difference exceeds 10% of the temperature value on the preset temperature-time curve of the battery cell.

8. The method for improving thermal management performance of a fast-charging battery according to claim 1, characterized in that: The heat-absorbing porous material is a carbon-based porous material, a porous metal foam material, or a composite structure of a porous metal foam material and a phase change material.

9. A system for improving the thermal management performance of a fast-charging battery, used to implement the method for improving the thermal management performance of a fast-charging battery according to any one of claims 1 to 8, characterized in that: include: A liquid cooling plate is provided at one end of the battery pack; A plurality of battery cells are arranged on the end surface of the liquid cooling plate, the plurality of battery cells are arranged at intervals along the length extension direction of the liquid cooling plate, and the end surfaces of the plurality of battery cells in the width extension direction are provided with a heat-absorbing porous material, the heat-absorbing porous material is used to absorb heat from the battery cells; a flexible circuit disposed on a surface of the heat-absorbing porous material; The monitoring module is set on the surface of several battery cells and the water inlet and outlet of the liquid cooling plate to obtain the real-time battery cell temperature, the temperature difference between the inlet and outlet water of the liquid cooling plate, and the charging current; The execution module is electrically connected to the flexible circuit, and provides an input voltage to the heat-absorbing porous material through the flexible circuit, thereby changing the porosity of the heat-absorbing porous material and converting the heat on the surface of the battery cell into the surface energy of the heat-absorbing porous material; The control module is electrically connected to the monitoring module and the flexible circuit. The control module obtains the heat generated by the battery cell during charging and the theoretical fast charging time. It also obtains the input voltage of the heat-absorbing porous material and estimates the heat dissipation performance of the heat-absorbing porous material. The control unit evaluates the deviation between the actual temperature and the theoretical temperature under the current charging conditions and heat dissipation performance, and selectively adjusts the input voltage of the execution module.

10. The system for improving thermal management performance of fast-charging batteries according to claim 9, characterized in that: The monitoring module includes an NTC temperature sensor, a water temperature sensor and a clock circuit. The NTC temperature sensor is set on the surface of several batteries to obtain the maximum temperature of the battery cell surface; the water temperature sensor is set at the water outlet of the liquid cooling plate to obtain the outlet water temperature of the liquid cooling plate; the clock circuit is used to obtain real-time time.

Images