A thermal management method of a power battery uniform temperature plate and the uniform temperature plate

Abstract

The present application relates to the technical field of power battery thermal management, and particularly relates to a power battery heat management method and a heat spreader, the heat spreader comprising a first substrate and a second substrate, a plurality of wicks and a plurality of channels located in a sealed vacuum cavity; the method comprises calculating a heat flux density vector of a power battery interface in contact with the heat spreader and a temperature gradient vector inside the heat spreader based on a transient temperature field to determine whether the power battery interface is in a heat flow accumulation deviation state; determining a target heat spreader to be heat dispersed based on a thermal resistance deviation integral value of a single heat spreader; determining an adjustment local reinforced cooling strategy based on a distribution state of the target heat spreader, or adjusting a global cooling strategy based on a temperature gradient characteristic of the target heat spreader; and performing a heat exchange process based on the determined cooling strategy to complete dynamic thermal balance between all battery cells and the heat spreader. The present application improves the long-term operation stability of the power battery module.

Description

Technical Field

[0001] This invention relates to the field of power battery thermal management technology, and in particular to a thermal management method and a power battery heat exchanger plate. Background Technology

[0002] With the rapid development of new energy vehicles and energy storage, the energy density and charging / discharging power of power battery modules are constantly increasing. During charging and discharging, these modules generate a large amount of heat. If this heat cannot be dissipated in time and the temperature distribution between cells is uneven, it can lead to inconsistent degradation of the electrochemical performance of the cells, a decrease in cycle life, and in severe cases, localized overheating, lithium plating, or even thermal runaway, significantly impacting the safety and reliability of the power battery module. To address these issues, vapor chambers, as highly efficient heat transfer elements, are widely used in power battery thermal management systems. Their core function is to achieve rapid heat transfer and temperature equalization between cells through the evaporation-condensation cycle of the internal phase change working fluid, reducing the temperature difference between cells. Currently, existing vapor chamber thermal management methods lack accurate identification of abnormal thermal resistance at the interface between the vapor chamber and the cells, making it impossible to accurately pinpoint the causes of heat flow accumulation deviations. Thermal compensation measures are not targeted enough, making it difficult to effectively solve the problem of localized heat accumulation caused by the decay of the vapor chamber's heat distribution function, thus failing to fully guarantee the long-term stable operation of the power battery module.

[0003] Chinese Patent Application Publication No. CN119603934A discloses a thermal conductivity control method and device for a heat sink module of a vapor chamber, relating to the field of intelligent thermal conductivity control technology. The method includes: monitoring and acquiring real-time operating parameters of the heat source area; analyzing heat load changes within a predetermined time window to generate a predicted temperature rise rate distribution; performing regional discretization evaluation on the real-time heat source temperature distribution and the predicted temperature rise rate distribution to obtain the high heat distribution dispersion coefficient and the temperature rise distribution dispersion coefficient; setting an adaptive thermal conductivity strategy based on the high heat distribution dispersion coefficient and the temperature rise distribution dispersion coefficient, and executing heat dissipation control of the heat source area. This application solves the technical problem that existing methods struggle to achieve rapid and accurate thermal conductivity adjustment under dynamic heat loads, leading to low thermal management efficiency and affecting the overall performance and reliability of servers. It allows for the setting of matching thermal conductivity control parameters according to the actual heat load state, significantly improving heat dissipation efficiency and ensuring stable and reliable server operation.

[0004] The existing technology still has the following problems: it cannot accurately identify the abnormal thermal resistance and heat flow accumulation deviation at the interface between the heat spreader and the cell; the thermal compensation measures lack specificity; it is difficult to solve the problem of local heat accumulation caused by the decay of the heat spreader's heat dissipation function; and it cannot fully guarantee the long-term stable operation of the power battery module. Summary of the Invention

[0005] To address this issue, the present invention provides a thermal management method and a heat exchanger for a power battery, which overcomes the problem in the prior art where the inability to accurately identify abnormal thermal resistance and heat flow accumulation deviation at the interface between the heat exchanger and the battery cell leads to poor long-term operational stability of the power battery module.

[0006] To achieve the above objectives, in one aspect, the present invention provides a thermal management method for a power battery heat exchanger, comprising:

[0007] Several heat exchange plates are installed in the power battery module to facilitate heat conduction between the cells;

[0008] Real-time monitoring of the transient temperature field of the power battery module during charging and discharging;

[0009] Based on the transient temperature field, the heat flux density vector of the power battery interface in contact with the cell and the temperature gradient vector inside the heat exchanger are determined to determine whether the power battery interface is in a state of heat flux accumulation deviation.

[0010] In response to the heat flow accumulation deviation state, based on the thermal resistance deviation integral value of a single heat exchanger in the interface thermal resistance distribution diagram of the heat exchanger, at least one target heat exchanger to be dispersed is determined, wherein the target heat exchanger is a heat exchanger whose thermal resistance deviation integral value exceeds a preset integral value.

[0011] Based on the distribution state of the target vapor chamber, determine the strategy to adjust the local enhanced cooling or adjust the global cooling strategy based on the temperature gradient characteristics of the target vapor chamber.

[0012] The heat exchange process is performed based on a defined cooling strategy to achieve dynamic thermal equilibrium between all cells and the vapor chamber.

[0013] Furthermore, the process of determining whether the power battery interface is in a state of heat flow accumulation deviation based on the heat flux density vector and the temperature gradient vector includes:

[0014] The difference between the heat flux density vector of a single power battery interface and the standard heat flux vector is used to obtain the temperature difference driving force vector;

[0015] The thermal difference driving force vectors of all power battery interfaces are superimposed in the spatial thermal field to obtain the heat flow accumulation deviation vector;

[0016] The amplitude of the accumulated heat flow deviation vector is compared with a preset amplitude;

[0017] Based on the comparison result that the amplitude is greater than the preset amplitude, it is determined that the power battery interface is in a state of heat flow accumulation deviation.

[0018] Furthermore, the process of determining at least one target heat-dispersing plate based on the integral value of the thermal resistance deviation of a single heat-dispersing plate includes:

[0019] The integral value of the thermal resistance deviation is compared with the preset integral value;

[0020] The heat spreader with a thermal resistance deviation integral value greater than the preset integral value is determined as the target heat spreader for heat dispersion.

[0021] Furthermore, the process of adjusting the local enhanced cooling strategy based on the distribution state of the target heat exchanger includes:

[0022] Determine the spatial distribution of the target heat exchange plates in the power battery module;

[0023] Based on the determination that the spatial distribution of the target heat exchange plates in the power battery module is a clustered distribution, the preset temperature for adjusting and activating local enhanced cooling is determined.

[0024] Furthermore, the process of adjusting the preset temperature for initiating localized enhanced cooling includes:

[0025] Determine the aggregation density of the target isothermal plate for the aggregation distribution;

[0026] The aggregation density is compared with a preset density;

[0027] Based on the comparison between the aggregate density and the preset density, several temperature adjustment coefficients are set to reduce the preset temperature for initiating local enhanced cooling.

[0028] Furthermore, the process of determining the adjustment of the global cooling strategy based on the distribution state of the target heat spreader includes:

[0029] Determine the spatial distribution of the target heat exchange plates in the power battery module;

[0030] Based on the determination that the spatial distribution of the target heat exchange plates in the power battery module is dispersed, a global cooling strategy is adjusted.

[0031] Furthermore, the process of adjusting the global cooling strategy includes:

[0032] The vector homogeneity index of the temperature gradient vectors of the target temperature distribution plates is compared with a preset index.

[0033] Based on the determination result that the vector homogeneity index is less than or equal to the preset index, a global cooling strategy with enhanced overall convection heat transfer is adopted.

[0034] Based on the determination that the vector homogeneity index is greater than the preset index, a global cooling strategy of partitioned flow control is adopted.

[0035] Furthermore, the vector homogeneity index is the standard deviation of the cosine of the angle between the direction of the temperature gradient vector of a single target temperature isotherm and the direction of the average temperature gradient vector of all target temperature isotherms.

[0036] Furthermore, the global cooling strategy employing zoned flow control includes:

[0037] The flow rate adjustment coefficient is determined based on the integral value of the thermal resistance deviation of the target vapor chamber. The liquid cooling flow rate of the grid partition of the liquid cooling plate corresponding to the target vapor chamber is adjusted according to the corresponding flow rate adjustment coefficient.

[0038] The flow rate adjustment coefficient is determined based on the integral value of the thermal resistance deviation of the target vapor chamber in the grid partition of the liquid cooling plate.

[0039] On the other hand, the present invention also provides a power battery heat exchange plate, comprising:

[0040] A first substrate and a second substrate are symmetrically arranged vertically, and a plurality of liquid-absorbing cores and a plurality of channels are fixed on the inner surface of the first substrate and located within a sealed vacuum cavity formed by the first substrate and the second substrate.

[0041] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention accurately collects the transient temperature field of the power battery module from multiple dimensions, combines Fourier's thermal conductivity law with finite element simulation technology, accurately calculates the heat flux density vector at the interface between the heat exchanger and the battery cell, and the temperature gradient vector inside the heat exchanger. Based on the spatial superposition of the temperature difference driving force vector, the heat flux accumulation deviation vector is obtained, and its amplitude is used as a quantitative judgment index for global thermal imbalance. This effectively eliminates the interference of local temperature fluctuations and measurement point errors, and achieves accurate identification of the heat flux accumulation deviation state at the power battery interface. It can promptly detect hidden dangers such as local heat accumulation and increased temperature difference between the battery cells caused by the decay or failure of the heat exchanger's heat dissipation function, and avoid problems such as the degradation of the consistency of the battery cell's electrochemical performance and the reduction of cycle life caused by the continuous expansion of the heat flux deviation, thereby improving the long-term operational stability of the power battery module.

[0042] Furthermore, based on the interface thermal resistance distribution map, this invention obtains the thermal resistance deviation integral value by calculating the area integral of the absolute difference between the actual thermal resistance and the standard thermal resistance at the contact interface of a single heat spreader. This integral value quantitatively characterizes the overall heat dissipation capability of a single heat spreader at the spatial global level, breaking through the limitation that local thermal resistance deviations cannot reflect the overall abnormality of the heat spreader. Based on the integral value, the target heat spreader with abnormal heat dissipation function is accurately located, ensuring that thermal compensation measures are applied to the abnormal heat spreader, suppressing the spread of thermal imbalance from the source, ensuring balanced heat transfer between cells, and thus further improving the long-term operational stability of the power battery module.

[0043] Furthermore, based on the spatial distribution and temperature gradient characteristics of the target heat exchange plate, this invention adaptively matches the cooling strategy. It determines whether the heat exchange plate is clustered or dispersed by the coefficient of variation of the interval distance. When clustered, it adjusts the preset temperature for local enhanced cooling. When dispersed, it selects the overall convective heat transfer enhancement mode or the zoned flow rate control mode by combining the vector isotropic index. The zoned flow rate control calculates the adjustment coefficient by the integral value of thermal resistance deviation, so as to achieve precise matching of the flow rate of the liquid cooling plate grid. This makes the cooling intensity highly compatible with the degree of thermal imbalance and spatial distribution, effectively improving the heat exchange efficiency, quickly alleviating local heat accumulation, balancing the cell temperature, avoiding safety risks such as local overheating and lithium plating, and thus further improving the long-term operational stability of the power battery module.

[0044] Furthermore, this invention optimizes the mechanical structure and working principle of the vapor chamber. It adopts a symmetrical double-substrate seal to form a vacuum cavity, with the liquid wick and cavity channels alternately distributed. The liquid wick drives the phase change working fluid to flow back through capillary force, and the cavity channels provide a low-resistance channel for vapor diffusion. Combined with substrate materials with excellent compatibility such as copper and aluminum alloys and efficient working fluids such as deionized water, the heat transfer efficiency and heat equalization capacity of the vapor chamber are significantly improved, ensuring rapid heat transfer between cells and reducing the generation of heat flow accumulation deviation from the hardware level. At the same time, the arrangement of the vapor chamber vertically inserted between the cells and the lower end attached to the partitioned liquid cooling plate constructs an efficient heat transfer link, accelerates heat dissipation, and ensures that the cells operate in a balanced temperature field, thereby further improving the long-term operational stability of the power battery module. Attached Figure Description

[0045] Figure 1 This is a flowchart of a thermal management method for a power battery heat exchanger according to an embodiment of the present invention;

[0046] Figure 2 This is a flowchart illustrating how to determine whether the power battery interface is in a state of heat flow accumulation deviation, as described in an embodiment of the present invention.

[0047] Figure 3 This is a flowchart illustrating the process of determining the target heat spreader for heat dispersion in an embodiment of the present invention.

[0048] Figure 4 This is a schematic diagram of the internal structure of the power battery heat exchanger according to an embodiment of the present invention;

[0049] In the figure: 1. First substrate, 2. Liquid suction core, 3. Cavity, 4. Reserved hole. Detailed Implementation

[0050] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0051] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0052] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0053] Please see Figure 1 The diagram shown is a flowchart of the thermal management method of the power battery heat exchanger plate according to an embodiment of the present invention.

[0054] The thermal management method for a power battery heat exchanger according to an embodiment of the present invention includes:

[0055] Step S1: Set up several heat exchange plates in the power battery module to conduct heat between the cells.

[0056] Step S2: Monitor the transient temperature field of the power battery module during the charging and discharging process in real time;

[0057] Step S3: Based on the transient temperature field, calculate the heat flux density vector at the power battery interface where the heat spreader plate contacts the battery cell and the temperature gradient vector inside the heat spreader plate to determine whether the power battery interface is in a state of heat flux accumulation deviation.

[0058] Step S4: In response to the heat flow accumulation deviation state, based on the thermal resistance deviation integral value of a single heat exchanger in the interface thermal resistance distribution diagram of the heat exchanger, at least one target heat exchanger to be dispersed is determined, wherein the target heat exchanger to be dispersed is a heat exchanger whose thermal resistance deviation integral value exceeds a preset integral value.

[0059] Step S5: Based on the distribution state of the target heat distribution plate, determine the local enhanced cooling strategy or adjust the global cooling strategy based on the temperature gradient characteristics of the target heat distribution plate.

[0060] Step S6: Perform a heat exchange process based on the determined cooling strategy to achieve dynamic thermal balance between all cells and the heat exchange plate.

[0061] Specifically, the arrangement of the heat spreader in the power battery module is as follows: a sheet-like heat spreader is vertically inserted into the gap between two adjacent cells, ensuring that each heat spreader simultaneously adheres to the surface of both cells. The specific parameters of the heat spreader are: thickness range of 2mm-5mm, length consistent with cell height, and width matching cell thickness. The arrangement ratio of heat spreader to cells in the module is 1:2, that is, one heat spreader is arranged between every two cells, ensuring that the heat from the cells can be quickly transferred to the heat spreader.

[0062] The liquid cooling plate is located at the bottom of the battery module. The lower end of the heat spreader is in direct contact with the upper surface of the liquid cooling plate. Heat is transferred from the battery cell to the heat spreader, and then conducted through the heat spreader to the area at the bottom that is in contact with the liquid cooling plate. Finally, it is carried away by the coolant. The liquid cooling plate consists of several grid partitions. The grid partitions can be divided according to the following criteria: each grid partition corresponds to the projection area of ​​3-5 heat spreaders. The size of a single grid partition is 50mm×50mm-100mm×100mm, and the specific size is not limited. Each grid partition has an independent liquid inlet and return outlet, and the liquid cooling flow rate can be adjusted independently.

[0063] Specifically, the transient temperature field of the power battery module during charging and discharging is monitored in real time. The temperature acquisition frequency is 1Hz-5Hz, dynamically adjusted according to the charge / discharge rate. 5Hz is used when the charge / discharge rate is ≥1C, and 1Hz is used when the charge / discharge rate is <1C. Any one or more of the following combinations can be used for acquisition, and the specific acquisition process is not limited:

[0064] Method 1: Real-time data acquisition using a thermocouple array. Select T-type or K-type miniature thermocouples with a temperature range of -50℃ to 150℃ and an accuracy of ±0.5℃. These thermocouples are placed at locations including, but not limited to, the center, corners, terminals, cell gaps, module housing, and the surface of the heat spreader plate of the battery cell. At least three measurement points are arranged on each battery cell: one at the center, one at each of the two corners, and one every 50mm on the surface of the heat spreader plate. 2 Set up one measuring point and use a multi-channel temperature acquisition instrument with ≥32 channels to simultaneously collect the real-time temperature of each position during the charging and discharging process of the power battery module;

[0065] Method 2: Use a fiber Bragg grating sensor with a temperature measurement accuracy of ±0.1℃ and a temperature measurement range of -40℃ to 120℃. Deploy the sensor on the surface of the battery cell, with the laying path consistent with the length direction of the battery cell. At least one fiber is laid on each battery cell. Based on optical frequency domain reflection technology or Rayleigh scattering principle, continuous temperature measurement is performed along the entire length of the fiber Bragg grating sensor, with a measurement resolution of 1mm.

[0066] Specifically, the collected raw instantaneous temperatures are synchronized with the sampling timestamps and sampling locations in time and calibrated in spatial coordinates to form a set of discrete temperature points at the same time. Using the discrete temperature points, a spatial interpolation algorithm is used, preferably Kriging interpolation with an interpolation accuracy of ≤0.3℃, to calculate the temperature of any spatial point within the power battery module, generating a continuous temperature field at the same time. The continuous temperature field at each time moment is generated sequentially according to the sampling time order, and the continuous temperature fields at individual time moments are connected in series along the time axis to form a transient temperature field that changes continuously with time. This is existing technology and will not be described in detail here.

[0067] Specifically, the heat flux density vector refers to the vector obtained by multiplying the thermal conductivity of the isothermal plate material by the negative value of the temperature gradient vector at the interface, according to Fourier's law. Its direction is perpendicular to the isothermal surface and points in the direction of decreasing temperature, and its magnitude is the heat flow rate through a unit area per unit time. The temperature gradient vector refers to the rate of change of temperature inside the isothermal plate in space, and its direction is through the normal direction of the isothermal surface and points in the direction of increasing temperature. The heat flux density vector and temperature gradient vector are obtained using finite element simulation calculations such as COMSOL. A three-dimensional geometric model of a power battery pack, including a heat spreader and battery cells, is pre-constructed at a scale of 1:1. The battery cells adopt a cylindrical or square structure. The interface between the heat spreader and the battery cells is modeled according to actual dimensions. Parameters such as the thermal conductivity, density, and specific heat capacity of the heat spreader are input into the model. Transient temperature field data is imported as boundary conditions. Based on the finite element discretization method within the software, tetrahedral mesh discretization is preferred, with a mesh size of 1mm-5mm. The thermal conductivity differential equation is solved, and the heat flux density vector at the interface between the heat spreader and the battery cells and the temperature gradient vector inside the heat spreader are output. This is existing technology and will not be elaborated further.

[0068] Please see Figure 2 As shown, it is a flowchart of an embodiment of the invention for determining whether the power battery interface is in a state of heat flow accumulation deviation.

[0069] Specifically, the process of determining whether the power battery interface is in a state of heat flow accumulation deviation based on the heat flux density vector and the temperature gradient vector includes:

[0070] The difference between the heat flux density vector of a single power battery interface and the standard heat flux vector is used to obtain the temperature difference driving force vector;

[0071] The thermal difference driving force vectors of all power battery interfaces are superimposed in the spatial thermal field to obtain the heat flow accumulation deviation vector;

[0072] The amplitude of the accumulated heat flow deviation vector is compared with a preset amplitude;

[0073] Based on the comparison result that the amplitude is greater than the preset amplitude, it is determined that the power battery interface is in a state of heat flow accumulation deviation.

[0074] Based on the comparison result that the amplitude is less than or equal to the preset amplitude, it is determined that the power battery interface is not in a state of heat flow accumulation deviation.

[0075] Specifically, the standard heat flux vector refers to the average rated heat flux density vector per unit area on the power battery interface where the heat spreader contacts the battery cell under ideal thermal conduction conditions, with an ambient temperature of 25±2℃, a charge / discharge rate of 0.5C, an initial cell temperature of 25℃, and no heat loss. It is the spatial arithmetic mean vector of the actual heat flux density vectors of all power battery interfaces under ideal thermal conduction conditions.

[0076] Specifically, the temperature difference driving force vectors of all power battery interfaces are superimposed in the spatial thermal field. That is, the vector algebra summation method is used, without considering spatial weights, and the x, y, and z components of all vectors are summed directly to obtain the total vector components, so as to obtain the heat flow accumulation deviation vector.

[0077] In the same three-dimensional Cartesian coordinate system, any temperature difference driving force vector It can be uniquely determined by the vector magnitude |Δq|, azimuth angle φ, and elevation angle θ, where φ is the angle between the projection of the temperature difference driving force vector onto the first plane formed by the x-axis and y-axis and the x-axis, and θ is the angle between the temperature difference driving force vector and the first plane. Its spatial component expression is:

[0078]

[0079] To illustrate the superposition process, the temperature difference driving force vector at the interfaces of the three power batteries within the power battery module is used. , , For example, perform trigonometric component decomposition on each vector:

[0080] The first vector:

[0081]

[0082] The second vector:

[0083]

[0084] The third vector:

[0085]

[0086] Summing the components in the x, y, and z directions separately:

[0087]

[0088] Substitute the numerical values ​​into the calculation:

[0089]

[0090] The cumulative heat flux deviation vector is synthesized from the total components, and its amplitude is calculated as the vector magnitude:

[0091]

[0092] Substituting the components yields the amplitude of the heat flow accumulation deviation vector, which is then compared with a preset amplitude to determine whether the system is in a heat flow accumulation deviation state.

[0093] In practice, when there are more than 3 interfaces, the same direct algebraic superposition rule of components is still used. No spatial weighting coefficient is introduced, no coordinate transformation is performed, and only the x, y, and z components of all temperature difference driving force vectors are summed.

[0094] Specifically, the magnitude of the heat flow accumulation deviation vector is the same as the modulus of the heat flow accumulation deviation vector.

[0095] Specifically, the preset amplitude value is preferably 3×10. 4 W / m 2 The optimal value was determined through the following experimental tests: A square power battery module was used, with specifications of 10 series and 5 parallel cells, a cell capacity of 200Ah, and individual cell dimensions of 50mm×100mm×150mm. A copper sheet-like heat spreader with a thickness of 3mm and a thermal conductivity of 380W / (m·K) was used. The initial flow rate of the liquid cooling plate was 8L / min, and the coolant was a 50% ethylene glycol aqueous solution. The experimental environment was controlled to an ideal thermal conduction state. First, the standard heat flux vector under ideal conditions was measured. Then, the charge / discharge rate and ambient temperature were adjusted, with the rate range from 0.5C to 2C and the ambient temperature range from -10℃ to 45℃, to simulate the change in heat flux density vector under different operating conditions. The correlation between the cumulative heat flux deviation vector amplitude and the temperature difference between cells was recorded in real time. Verification was performed using 30 parallel experiments. When the amplitude ≤ 3×10... 4 W / m 2 When the temperature difference between the cells is ≤3℃, the heat dissipation function of the heat spreader is normal; when the amplitude exceeds 3×10 4 W / m 2 At that moment, the temperature difference between the battery cells instantaneously exceeded 5°C, the heat transfer efficiency of the heat spreader decreased by more than 25%, and the heat spreader function showed a significant decline. Therefore, the 3×10 4 W / m 2 This serves as a threshold for judgment, ensuring the accuracy and reliability of the judgment results.

[0096] Specifically, the function of the heat spreader is to achieve rapid heat conduction and temperature equalization between battery cells. If a heat flow accumulation deviation occurs at the interface between the heat spreader and the battery cells, it indicates that the heat spreader's heat equalization function has weakened or failed. Heat cannot be transferred and equalized between the cells in a timely manner, leading to problems such as localized heat accumulation and increased temperature differences between cells. Prolonged exposure to this state will result in inconsistent degradation of the cell's electrochemical performance and reduced cycle life. In severe cases, it can even induce localized overheating, lithium plating, and even thermal runaway. Real-time determination of the interface heat flow accumulation deviation can promptly identify heat spreader anomalies and potential module thermal imbalances, providing a direct basis for the adaptive adjustment of the thermal management system. This helps to suppress the continuous expansion of heat flow deviation, ensuring that the cells always operate in a balanced temperature field with a temperature difference between cells ≤3℃. The heat flow accumulation deviation vector contains both information on the direction and degree of thermal imbalance. Its amplitude, as a quantitative indicator of the severity of global thermal imbalance, can eliminate spatial interference and directly reflect the total cumulative amount of heat flow deviating from the ideal equilibrium state at the contact interface. Relying solely on localized heat flow deviations at a single interface is susceptible to instantaneous fluctuations and measurement point errors, failing to accurately reflect the overall heat accumulation level of the module. However, by spatially superimposing the temperature difference driving force vectors across the entire interface, the amplitude can characterize the total heat loss balance of the entire interface, effectively avoiding misjudgments caused by minor local deviations and improving the stability and reliability of the judgment results.

[0097] Please see Figure 3 As shown, it is a flowchart of determining the target heat spreader for heat dispersion in an embodiment of the present invention.

[0098] Specifically, the process of determining at least one target heat spreader based on the integral value of the thermal resistance deviation of a single heat spreader includes:

[0099] The integral value of the thermal resistance deviation is compared with the preset integral value;

[0100] The heat distribution plate whose thermal resistance deviation integral value is greater than the preset integral value is determined as the target heat distribution plate to be dispersed.

[0101] A heat spreader with a thermal resistance deviation integral value less than or equal to the preset integral value will not be used as a target heat spreader for heat dispersion.

[0102] Specifically, the interface thermal resistance distribution map is determined based on the transient temperature field. The determination process is as follows: the transient temperature field is spatially discretized using a rectangular discretization method, with a discrete element size of 5mm×5mm. Each heat spreader contact interface is divided into at least 20 discrete elements, resulting in several discrete elements. The instantaneous temperature distribution of several discrete elements at the power battery interface is extracted. Based on the instantaneous temperature distribution and temperature gradient vector, the normal heat flux density of each discrete element is obtained. The solution process is existing technology and will not be elaborated further. The interface thermal resistance is the ratio of the temperature difference on both sides of the discrete element to the normal heat flux density of the discrete element. The interface thermal resistance values ​​of each discrete element are mapped and arranged according to their actual spatial coordinates at the contact interface between the heat spreader and the battery cell to form the interface thermal resistance distribution map.

[0103] Specifically, the thermal resistance deviation integral value refers to the value obtained by integrating the area of ​​the absolute difference between the actual interface thermal resistance and the standard interface thermal resistance at each position on the single-sided interface where a single heat spreader contacts the battery cell. The standard interface thermal resistance refers to the arithmetic mean of the thermal resistance values ​​at the interface between the heat spreader and the battery cell of the power battery module under ideal thermal conduction conditions.

[0104] Specifically, the preferred value for the preset integral is 4 × 10. -6 m 4 The optimal value of K / W was determined through the following experimental tests: A power battery module and heat spreader of the same specifications as described above were used in the experiment. First, the standard interfacial thermal resistance under ideal thermal conduction conditions was measured. Then, by changing the contact pressure between the heat spreader and the battery cell (ranging from 0.1 MPa to 0.5 MPa), the actual interfacial thermal resistance variation under different contact conditions was simulated. The integral value of the thermal resistance deviation on one side of each heat spreader's contact interface was calculated, and the thermal conduction efficiency of the corresponding heat spreader was tested simultaneously. Verification was performed using 25 parallel experiments. When the integral value of the thermal resistance deviation is ≤4×10... -6 m 4 At a K / W ratio, the heat transfer efficiency of the heat spreader is ≥90%, achieving ideal heat distribution; when the integral value of the thermal resistance deviation exceeds 4×10 -6 m 4 At K / W, the heat transfer efficiency of the vapor chamber drops below 70%, making it unable to quickly transfer heat between the cells. Therefore, the efficiency of 4×10 -6 m 4 K / W is used as the threshold for determining the target temperature distribution plate.

[0105] Specifically, the vapor chamber achieves rapid heat conduction between battery cells through low thermal resistance. The integral value of thermal resistance deviation characterizes the actual heat dissipation capability of the vapor chamber. If the integral value of thermal resistance deviation of a single vapor chamber exceeds a threshold, it indicates that the vapor chamber can no longer achieve ideal heat conduction, which is the main reason for the overall heat flow accumulation deviation. Therefore, vapor chambers with abnormal heat dissipation capability can be accurately located based on the integral value of thermal resistance deviation.

[0106] Specifically, the process of determining the local enhanced cooling strategy based on the distribution state of the target heat spreader includes:

[0107] Determine the spatial distribution of the target heat exchange plates in the power battery module;

[0108] Based on the determination that the spatial distribution of the target heat exchange plates in the power battery module is a clustered distribution, the preset temperature for adjusting and activating local enhanced cooling is determined.

[0109] Specifically, the process of determining and adjusting the global cooling strategy based on the distribution state of the target heat spreader includes:

[0110] Determine the spatial distribution of the target heat exchange plates in the power battery module;

[0111] Based on the determination that the spatial distribution of the target heat exchange plates in the power battery module is dispersed, a global cooling strategy is determined to be adjusted.

[0112] The vector homogeneity index of the temperature gradient vectors of the target temperature distribution plates is compared with a preset index.

[0113] Based on the determination result that the vector homogeneity index is less than or equal to the preset index, a global cooling strategy with enhanced overall convection heat transfer is adopted.

[0114] Based on the determination that the vector homogeneity index is greater than the preset index, a global cooling strategy of partitioned flow control is adopted.

[0115] Specifically, the process of determining the distribution state of the target heat spreader in the battery module includes:

[0116] Determine the interval distance between two adjacent target heat spreaders;

[0117] The coefficient of variation of several of the aforementioned interval distances is determined as the state characterization index;

[0118] The state characterization index is compared with a preset characterization index;

[0119] Based on the comparison result that the state characterization index is greater than the preset characterization index, the distribution state of the target temperature distribution plate in the battery module is determined to be a dispersed distribution.

[0120] Based on the comparison result that the state characterization index is less than or equal to the preset characterization index, the distribution state of the target temperature distribution plate in the battery module is determined to be a concentrated distribution.

[0121] Specifically, the preset characterization index is preferably set at 15%, and this preferred value was determined through the following experimental tests:

[0122] The experiment used power battery modules of the above specifications and artificially set up five target temperature distribution scenarios:

[0123] 1. Centralized distribution: 10 target heat spreaders are clustered in the central area of ​​the module;

[0124] 2. Distributed arrangement: 10 target heat spreaders are evenly distributed throughout the module.

[0125] 3. Semi-centralized and semi-dispersed: 6 centralized and 4 dispersed areas;

[0126] 4. Local dispersion: 5 blocks are concentrated, and 5 blocks are dispersed in adjacent areas;

[0127] 5. Random distribution: 10 target temperature equalization plates are randomly arranged;

[0128] The coefficient of variation (COP) of the distance between adjacent target vapor chambers was calculated for each scenario, and the extent and degree of heat accumulation on the target vapor chambers were observed. Validated through 20 sets of experiments, when the COP is ≤15%, the spacing between the target vapor chambers fluctuates by ≤2cm, indicating a concentrated heat accumulation area, which can be classified as a concentrated distribution; when the COP is >15%, the spacing fluctuates by >2cm, indicating a dispersed heat accumulation area, which can be classified as a dispersed distribution. This threshold can accurately distinguish between the two distribution states, adapting to the selection of subsequent cooling strategies.

[0129] Specifically, the process of adjusting the preset temperature for initiating localized enhanced cooling includes:

[0130] Determine the aggregation density of the target isothermal plate for the aggregation distribution;

[0131] The aggregation density is compared with a preset density;

[0132] Based on the comparison between the aggregate density and the preset density, several temperature adjustment coefficients are set to reduce the preset temperature for initiating local enhanced cooling.

[0133] Specifically, based on the comparison result that the aggregation density is greater than or equal to the preset density, a preset temperature for initiating local enhanced cooling is determined by lowering the first temperature adjustment coefficient.

[0134] Based on the comparison result that the aggregation density is less than the preset density, the preset temperature for initiating local enhanced cooling is determined by lowering the second temperature adjustment coefficient.

[0135] Specifically, the clustering density refers to the percentage of target heat exchangers within a preset radius centered on any target heat exchanger, relative to the total number of heat exchangers. The preferred preset radius is 10cm. This radius was determined as follows: using modules of the aforementioned specifications with a heat exchanger spacing of 2cm, the coverage effect of the clustered areas of the target heat exchangers was tested at five preset radii: 5cm, 8cm, 10cm, 15cm, and 20cm. The number of clustered areas completely covered at different radii was recorded. After 15 sets of experiments, it was verified that radii of 5cm and 8cm could not completely cover the concentrated distribution of target heat exchangers, with a coverage rate ≤70%. Radius of 15cm and 20cm covered heat exchangers in non-clustered areas, with a redundancy coverage rate ≥30%. A radius of 10cm completely covered more than 90% of the concentrated distribution area without significant redundancy. Considering the horizontal heat transfer range of the heat exchanger, approximately 8-12cm, 10cm was determined to be the preferred preset radius.

[0136] Specifically, the preferred preset density is 50%, determined through the following experimental tests: Using modules of the above specifications, different aggregation densities (30%, 40%, 50%, 60%, and 70%) were set. The local heat accumulation temperature was tested at each aggregation density, with a charge / discharge rate of 1C and an ambient temperature of 25℃. The time it took for the heat accumulation temperature to exceed the cell's safe temperature of 45℃ was recorded. After 18 sets of experiments, it was verified that when the aggregation density was ≥50%, the time for the local heat accumulation temperature to reach 45℃ was ≤10 minutes, indicating a higher risk of heat accumulation, requiring a significant reduction in the activation temperature for enhanced local cooling. When the aggregation density was <50%, the time for the local heat accumulation temperature to reach 45℃ was ≥25 minutes, indicating a lower risk of heat accumulation, requiring only a moderate reduction in the activation temperature. Therefore, 50% was determined to be the preferred preset density.

[0137] The preferred values ​​for the first temperature regulation coefficient are 0.83 and the preferred values ​​for the second temperature regulation coefficient are 0.89. These were determined through the following experimental tests: The experiments used a preset local cooling temperature of 40℃ as the baseline for normal module startup. The cooling effect and energy consumption were tested at the first coefficient range (0.8, 0.83, 0.86) and the second coefficient range (0.87, 0.89, 0.92). After 22 sets of experiments, it was verified that the first coefficient of 0.83 can reduce the startup temperature to 33.2℃ and lower the local heat accumulation temperature below 40℃ within 8 minutes, with a reasonable increase in energy consumption. The second coefficient of 0.89 can reduce the startup temperature to 35.6℃ and lower the local heat accumulation temperature below 40℃ within 12 minutes, balancing cooling effect and energy consumption. Therefore, the preferred values ​​for both coefficients were determined, as they can quickly respond to local heat accumulation while avoiding over-cooling.

[0138] Specifically, the vector homogeneity index is the standard deviation of the cosine of the angle between the temperature gradient vector direction of a single target temperature distribution plate and the average temperature gradient vector direction of all target temperature distribution plates. The smaller the vector homogeneity index, the closer the temperature gradient vector directions are to each other, and the more uniform the overall thermal imbalance direction of the module is.

[0139] Specifically, the preset index is preferably 0.3, and this preferred value was determined through the following experimental tests:

[0140] The experiment used modules of the above specifications to simulate different thermal imbalance scenarios:

[0141] 1. The thermal imbalance direction of all target temperature equalizers is consistent;

[0142] 2. The thermal imbalance direction is the same for half of the target heat exchange plates, and opposite for the other half;

[0143] 3. The direction of thermal imbalance of all target temperature equalizers is random;

[0144] The vector homogeneity index was calculated for each scenario, and the adaptation effect of different global cooling strategies was tested. Through 20 sets of experiments, it was verified that when the vector homogeneity index ≤ 0.3, the thermal imbalance direction of more than 85% of the target vapor chambers was basically consistent, and the overall convection heat transfer enhancement strategy could eliminate the heat flow accumulation deviation in ≤ 15 minutes. When the vector homogeneity index > 0.3, the thermal imbalance direction of the target vapor chambers was dispersed, and the overall heat transfer enhancement strategy could not be accurately adapted; a zoned flow control strategy was required. Therefore, 0.3 was determined as the preferred preset index.

[0145] Specifically, the global cooling strategy of enhancing overall convective heat transfer is to increase the total flow rate of the entire liquid cooling system of the power battery module, thereby improving the overall heat transfer intensity. The increase in total flow rate is positively correlated with the average value of the thermal resistance deviation integral value of the target heat exchange plate, and the increase in total flow rate does not exceed the maximum allowable flow rate of the liquid cooling system of 50L / min.

[0146] Specifically, enhanced local cooling is achieved by increasing the flow rate of the corresponding liquid cooling plate grid partition.

[0147] Specifically, the global cooling strategy employing zoned flow control works as follows: A flow adjustment coefficient is determined based on the integral value of the thermal resistance deviation of the target vapor chamber. This coefficient is then used to adjust the liquid cooling flow rate of the corresponding grid partition of the liquid cooling plate. The flow adjustment coefficient is calculated as: 1 + 0.2 × (Sum of the integral values ​​of the thermal resistance deviation of all target vapor chambers within a single grid partition - Average value of the integral values ​​of the thermal resistance deviation of the target vapor chambers in all grid partitions of the liquid cooling plate) / Average value of the integral values ​​of the thermal resistance deviation of the target vapor chambers in all grid partitions. Multiplying the determined flow adjustment coefficient by the original liquid cooling flow rate of a single grid partition yields the adjusted liquid cooling flow rate of that grid partition. The coefficient 0.2 in the formula has been experimentally verified to ensure precise matching between the flow adjustment and the deviation of the integral value of the thermal resistance deviation, guaranteeing heat exchange efficiency while avoiding energy waste.

[0148] Specifically, the heat exchange process is executed based on a determined cooling strategy. The heat exchange execution cycle is consistent with the temperature acquisition cycle. The transient temperature field, heat flux density vector and temperature gradient vector after heat exchange are acquired in real time. The cooling strategy is dynamically adjusted until the amplitude of the cumulative heat flux deviation vector is ≤ the preset amplitude and the temperature difference between cells is ≤ 3℃, thus completing the dynamic thermal balance between all cells and the heat exchange plate.

[0149] When the thermal resistance deviation integral value of the target vapor chamber exceeds 1.5 times the preset integral value, in addition to implementing the corresponding cooling strategy, an alarm signal is issued simultaneously. The alarm signal can be transmitted to the BMS system to remind staff to check the contact status of the vapor chamber. If the heat flow accumulation deviation is not eliminated after 3 consecutive execution cycles, the emergency cooling mode is activated, and the total flow rate of the liquid cooling system is increased to the maximum allowable flow rate until the deviation is eliminated, further improving the safety and reliability of thermal management.

[0150] Please see Figure 4 As shown, it is a schematic diagram of the internal structure of the power battery heat exchanger in an embodiment of the present invention.

[0151] The power battery temperature distribution plate of this invention includes:

[0152] A first substrate 1 and a second substrate (not shown in the figure) are arranged symmetrically vertically. Several liquid-absorbing cores 2 and several channels 3 are fixed to the inner surface of the first substrate 1 and located within the sealed vacuum cavity formed by the first substrate 1 and the second substrate. Several pre-drilled holes 4 are distributed on the surface of the first substrate for mounting.

[0153] The liquid-absorbing core 2 adopts a porous capillary structure, which is uniformly covered in the heat transfer area of ​​the temperature distribution plate to form a continuous capillary reflux channel. The condensed working fluid is driven to flow back to the evaporation zone by capillary force.

[0154] The cavity 3 is a steam flow channel inside the heat spreader plate. It is in the form of multiple sets of long strip grooves, arranged parallel to the heat transfer direction of the heat spreader plate, and alternately distributed with the liquid absorption core 2, providing space for the rapid diffusion of steam generated by phase change.

[0155] Specifically, porous capillary structures such as sintered copper powder, woven copper mesh, or grooved capillary structures are not limited to any particular type; the substrate material can be copper or aluminum-based composite materials with a thermal conductivity ranging from 180 W / (m·K) to 400 W / (m·K) and a density of 2700 kg / m³. 3 -8960kg / m 3 The specific heat capacity is 880 J / (kg·K)-385 J / (kg·K), and the specific parameters can be adjusted according to the module design requirements; the working fluid used for heat transfer can be deionized water, a mixture of ethanol and water, and there is no specific limitation.

[0156] Specifically, when the vapor chamber is in operation, the evaporation side region in contact with the heating cell absorbs heat, causing the phase change working fluid in the sealed vacuum chamber to vaporize into high-pressure steam. The steam quickly diffuses along the cavity 3 to the condensation side region in contact with the heat dissipation structure of the liquid cooling plate, releases heat, and condenses into a liquid state. The condensed liquid working fluid, driven by the capillary force of the liquid wick 2, flows back to the evaporation side along the structure of the liquid wick 2, completing one phase change cycle of evaporation-condensation-recirculation. This process is repeated to achieve rapid heat transfer and temperature uniformity, effectively balancing the temperature difference between the cells.

[0157] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A thermal management method for a power battery heat exchanger, characterized in that, include: Several heat exchange plates are installed in the power battery module to facilitate heat conduction between the cells; During the charging and discharging process of the power battery module, several original instantaneous temperatures on the interface between the heat exchange plate and the battery cell are monitored in real time to form several spatial discrete temperature point sets at the same time. A continuous temperature field at the same time is generated based on the spatial discrete temperature point sets by a spatial difference algorithm. The continuous temperature field is then connected in series along the time axis to form a transient temperature field. The heat flux density vector of the power battery interface is determined based on the transient temperature field. The difference between the heat flux density vector of a single power battery interface and the standard heat flux vector is obtained to obtain the temperature difference driving force vector. The amplitude of the heat flux accumulation deviation vector obtained by superimposing the spatial thermal field of all temperature difference driving force vectors is compared with the preset amplitude to determine whether the power battery interface is in the heat flux accumulation deviation state. In response to the heat flow accumulation deviation state, based on the thermal resistance deviation integral value of a single heat exchanger in the interface thermal resistance distribution diagram of the heat exchanger, at least one target heat exchanger to be dispersed is determined, wherein the target heat exchanger is a heat exchanger whose thermal resistance deviation integral value exceeds a preset integral value. Based on the determination that the target heat spreader is clustered in the power battery module, a strategy for adjusting the local enhanced cooling is determined. Based on the determination that the target heat spreader is spatially distributed in the power battery module, the global cooling strategy is adjusted. The heat exchange process is performed based on a defined cooling strategy to achieve dynamic thermal equilibrium between all cells and the vapor chamber.

2. The thermal management method for the power battery heat exchanger according to claim 1, characterized in that, The process of determining whether the power battery interface is in a state of heat flow accumulation deviation based on the comparison result of the amplitude of the heat flow accumulation deviation vector and a preset amplitude includes: The amplitude of the accumulated heat flow deviation vector is compared with a preset amplitude; Based on the comparison result that the amplitude is greater than the preset amplitude, it is determined that the power battery interface is in a state of heat flow accumulation deviation.

3. The thermal management method for a power battery heat exchanger according to claim 2, characterized in that, The process of determining at least one target vapor chamber for heat dispersion based on the integral value of the thermal resistance deviation of a single vapor chamber includes: The integral value of the thermal resistance deviation is compared with the preset integral value; The heat spreader with a thermal resistance deviation integral value greater than the preset integral value is determined as the target heat spreader for heat dispersion.

4. The thermal management method for the power battery heat exchanger according to claim 3, characterized in that, The process of adjusting the local enhanced cooling strategy based on the distribution state of the target heat exchanger includes: Determine the spatial distribution of the target heat exchange plates in the power battery module; Based on the determination that the spatial distribution of the target heat exchange plates in the power battery module is a clustered distribution, the preset temperature for adjusting and activating local enhanced cooling is determined.

5. The thermal management method for the power battery heat exchanger according to claim 4, characterized in that, The process of adjusting the preset temperature for initiating localized enhanced cooling includes: Determine the aggregation density of the target isothermal plate for the aggregation distribution; The aggregation density is compared with a preset density; Based on the comparison between the aggregate density and the preset density, several temperature adjustment coefficients are set to reduce the preset temperature for initiating local enhanced cooling.

6. The thermal management method for a power battery heat exchanger according to claim 5, characterized in that, The process of adjusting the global cooling strategy includes: The vector homogeneity index of the temperature gradient vectors of the target temperature distribution plates is compared with a preset index. Based on the determination result that the vector homogeneity index is less than or equal to the preset index, a global cooling strategy with enhanced overall convection heat transfer is adopted. Based on the determination result that the vector homogeneity index is greater than the preset index, a global cooling strategy of partitioned flow control is adopted. The vector homogeneity index is the standard deviation of the cosine of the angle between the direction of the temperature gradient vector of a single target temperature isotherm and the direction of the average temperature gradient vector of all target temperature isotherms.

7. The thermal management method for a power battery heat exchanger according to claim 6, characterized in that, Global cooling strategies employing zoned flow control include: The flow rate adjustment coefficient is determined based on the integral value of the thermal resistance deviation of the target vapor chamber. The liquid cooling flow rate of the grid partition of the liquid cooling plate corresponding to the target vapor chamber is adjusted according to the corresponding flow rate adjustment coefficient. The flow rate adjustment coefficient is determined based on the integral value of the thermal resistance deviation of the target vapor chamber in the grid partition of the liquid cooling plate.

8. A power battery heat exchanger, employing the thermal management method for the power battery heat exchanger as described in any one of claims 1-7, characterized in that, include: A first substrate and a second substrate are symmetrically arranged vertically, and a plurality of liquid-absorbing cores and a plurality of channels are fixed on the inner surface of the first substrate and located within a sealed vacuum cavity formed by the first substrate and the second substrate.

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