Method for Thermal Management and Thermal Runaway Suppression of Power Battery Based on Lumped Model

Abstract

The present disclosure belongs to the technical field of battery management, and provides a power battery thermal management and thermal runaway suppression method based on a lumped model, including the following steps: constructing a thermal management geometric structure of the power battery based on a liquid-cooled microchannel and a phase change material; obtaining physical property parameters of the thermal management geometric structure and establishing a heat generation model of a single battery; constructing a lumped model of the power battery according to heat generation models of multiple single batteries and physical property parameters in combination with an equivalent circuit; adding a thermal runaway spread suppression management module to the lumped model, predicting temperature changes of the power battery based on the lumped model, determining conditions for the power battery to trigger thermal runaway, and starting the liquid-cooled microchannel before reaching the thermal runaway trigger conditions of the power battery to suppress the spread of thermal runaway and achieve thermal management of the power battery.

Description

Technical Field

[0001] The present disclosure belongs to the technical field of battery management, and particularly relates to a power battery thermal management and thermal runaway suppression method based on a lumped model. Background Art

[0002] The statements in this section merely provide background technical information related to the present disclosure and do not necessarily constitute prior art.

[0003] Lithium-ion batteries are usually used as the power source for electric vehicles due to their advantages such as high energy and power density, no memory effect, and long cycle life. However, the safety of power batteries is the first problem to be considered and solved in the development of electric vehicles. With the continuous increase in battery energy density, battery thermal runaway accidents in electric vehicles occur frequently, which limits the large-scale application of electric vehicles. Therefore, research on power battery thermal management needs to be carried out.

[0004] The battery pack of an electric vehicle needs to apply real-time thermal management methods to ensure and predict the safe use of the battery. Currently, the thermal management methods for the battery pack under normal operating conditions at room temperature are relatively perfect, including thermal management methods such as air cooling, liquid cooling, phase change materials, and methods combining multiple thermal management methods.

[0005] As understood by the inventor, there are unreasonable problems with the current thermal management structure for suppressing the spread of thermal runaway. If the heat dissipation direction is the same as the direction of thermal runaway spread, it may even exacerbate the spread of thermal runaway; in addition, most of the existing thermal runaway spread models with a thermal management system are finite element models, which have a slow calculation speed and are difficult to apply to actual vehicles; and the existing fast prediction thermal runaway spread models do not have a thermal management system added. The existing fast prediction thermal runaway spread models use a heat transfer function based on an equivalent heat transfer experiment to quickly predict the spread of the battery after thermal runaway, and there is also a circuit model based on thermal resistance to quickly predict thermal runaway. The two cannot be organically combined, and there is a lack of a fast prediction of the thermal runaway spread situation under the suppression of a thermal management system. Summary of the Invention

[0006] To solve the above problems, the present disclosure proposes a power battery thermal management and thermal runaway suppression method based on a lumped model. A structure combining a phase change material and a liquid-cooled microchannel is used as a thermal management system to suppress the spread of thermal runaway. The possible spread direction of thermal runaway is fully considered, the liquid-cooling flow direction is vertical, there is no possibility of exacerbating the spread of thermal runaway, and the thermal runaway can be suppressed quickly and effectively.

[0007] According to some embodiments, the solution of the present disclosure provides a power battery thermal management and thermal runaway suppression method based on a lumped model, adopting the following technical solution:

[0008] A method for thermal management and thermal runaway propagation suppression of power batteries based on a lumped model, comprising the following steps:

[0009] Construct a thermal management geometric structure for the power battery based on liquid-cooled microchannels and phase change materials;

[0010] Obtain the physical property parameters of the thermal management geometric structure and establish a heat generation model for a single cell;

[0011] Construct a lumped model of the power battery according to the heat generation models of multiple single cells;

[0012] Add a thermal runaway propagation suppression management module to the lumped model, predict the temperature change of the power battery based on the lumped model, determine the conditions for the power battery to trigger thermal runaway, and start the liquid-cooled microchannels before reaching the thermal runaway trigger conditions of the power battery to suppress the thermal runaway propagation and achieve the thermal management of the power battery.

[0013] As a further technical limitation, during the process of constructing the thermal management geometric structure of the power battery, wrap the phase change material around each single cell, and arrange the liquid-cooled microchannels in the vertical direction of the single cell.

[0014] Further, when the single cell is operating normally, the thermal management geometric structure dissipates heat using the phase change material; when the single cell enters the thermal runaway state, the thermal management geometric structure starts the liquid-cooled microchannels to dissipate heat and suppress the thermal runaway propagation of the power battery.

[0015] As a further technical limitation, the heat generation model of the single cell includes the heat generation amount during the normal operation of the single cell and the heat generation amount during the thermal runaway of the single cell.

[0016] As a further technical limitation, the physical property parameters of the thermal management geometric structure include the heat capacity of the single cell, the thermal resistance of the single cell, the contact thermal resistance between single cells, the heat capacity of the thermal management material, the contact thermal resistance between the single cell and the thermal management material, the convective thermal resistance of the single cell, and the convective thermal resistance of the thermal management material.

[0017] Further, during the process of constructing the lumped model of the power battery, establish a lumped thermal resistance network of the power battery based on the established heat generation model of the single cell and the physical property parameters, and establish a lumped thermal resistance model of the power battery in combination with an equivalent circuit.

[0018] Specifically, after establishing the lumped thermal resistance network, the heat transfer characteristics of the battery, such as the heat capacity of the single cell, the conduction thermal resistance inside the single cell, and the contact thermal resistance between single cells, are obtained. The obtained lumped thermal resistance network is represented by an equivalent circuit, and the output of the equivalent current source represents the heat generation model of the single cell; the equivalent capacitance represents the heat capacity of the single cell; the equivalent resistance represents the conduction thermal resistance inside the battery, the contact thermal resistance between batteries, etc. Finally, the equivalent circuit is built using MATLAB Simulink.

[0019] Furthermore, the lumped thermal resistance network of the power battery includes the battery thermal resistance network during normal operation of the power battery and the power battery thermal resistance network with microchannels.

[0020] Furthermore, the lumped model is represented by an equivalent circuit composed of an equivalent current source, an equivalent resistance, and an equivalent capacitance; wherein, the output of the equivalent current source represents the heat generation model of the single cell; the equivalent capacitance represents the heat capacity of the single cell; the equivalent resistance represents the thermal resistance.

[0021] As a further technical limitation, the thermal runaway propagation suppression management module includes a phase change material module and a liquid cooling module; taking the phase change material module around the single cell as a whole, when the phase change material is heated to the melting temperature, the phase change material undergoes a phase change from solid to liquid.

[0022] Specifically, the thermal management module consists of a phase change material module and a liquid cooling module. When the single cell is operating normally, only the phase change material model in the thermal management is running, that is, only the phase change material dissipates heat; when the single cell enters the thermal runaway state, the liquid cooling module is started in the thermal management. At this time, the phase change material model and the liquid cooling module run simultaneously, and the liquid cooling and the phase change material dissipate heat together to suppress the thermal runaway propagation of the power battery; the method of adding the thermal management module to the equivalent circuit model is as follows. For the phase change material module, the phase change material around one battery is regarded as a whole. At the same time, because the phase change material will undergo a phase change from solid to liquid when heated to the melting temperature, the heat capacity of the phase change material around one battery is represented by a variable capacitance, and the contact thermal resistance between the battery and the thermal management material is represented by a resistance; for the liquid cooling module, in order to simulate the effect of the liquid cooling flow in the model, the liquid in a microchannel is divided into two parts, and the heat capacity of the entire microchannel is represented by two capacitances. The heat dissipation cycle is realized through the switch control of the circuit to simulate the liquid cooling.

[0023] As a further technical limitation, when determining the conditions for triggering thermal runaway of the power battery, when the temperature of the power battery exceeds the preset value of the thermal runaway temperature or the temperature rise rate of the power battery exceeds the preset value of the thermal runaway temperature rise rate, the power battery undergoes thermal runaway.

[0024] Compared with the prior art, the beneficial effects of the present disclosure are as follows:

[0025] Based on the structure combining phase change materials and liquid-cooled microchannels as a thermal management system to suppress the spread of thermal runaway, the present disclosure fully considers the possible spread direction of thermal runaway. The liquid-cooling flow direction is vertical, and there is no possibility of exacerbating the spread of thermal runaway, and it has a fast speed and good effect in suppressing thermal runaway. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings forming a part of this disclosure are used to provide a further understanding of the disclosure. The schematic embodiments and descriptions thereof of the disclosure are used to explain the disclosure and do not constitute an improper limitation of the disclosure.

[0027] Figure 1 is a flowchart of a method for thermal management and thermal runaway suppression of a power battery based on a lumped model in an embodiment of the present disclosure;

[0028] Figure 2 is a schematic structural diagram of a thermal management geometric structure of a power battery in an embodiment of the present disclosure;

[0029] Figure 3 is another schematic structural diagram of a thermal management geometric structure of a power battery in an embodiment of the present disclosure;

[0030] Figure 4 is a schematic diagram of a thermal resistance network structure of a power battery in an embodiment of the present disclosure;

[0031] Figure 5 is a schematic diagram of a thermal resistance network structure of a microchannel in an embodiment of the present disclosure;

[0032] Figure 6 is an equivalent circuit diagram of a lumped model in an embodiment of the present disclosure;

[0033] Figure 7 is a simulation schematic diagram of a microchannel in an embodiment of the present disclosure;

[0034] Figure 8(a) is a schematic diagram of the temperature change of a thermal runaway-triggered battery in an embodiment of the present disclosure;

[0035] Figure 8(b) is a schematic diagram of the temperature change of an adjacent battery in an embodiment of the present disclosure;

[0036] Figure 9 is a schematic diagram for comparing the calculation time of a model in an embodiment of the present disclosure;

[0037] Figure 10 is a schematic diagram of the temperature change of a thermal runaway-triggered battery (Battery-1) and an adjacent battery (Battery-2) in an embodiment of the present disclosure;

[0038] Figure 11It is a schematic diagram of the temperature changes of the thermal runaway-triggered battery and adjacent batteries without liquid cooling in the embodiments of the present disclosure;

[0039] Figure 12 It is a schematic diagram of the temperature changes of multiple batteries simultaneously triggering thermal runaway in the embodiments of the present disclosure;

[0040] Among them, 1. Battery No. 1, 2. Battery No. 2, 3. Battery No. 3, 4. Battery No. 4, 5. Battery No. 5, 6. Battery No. 6, 7. Battery No. 7, 8. Battery No. 8, 9. Battery No. 9, 10. Battery No. 10, 11. Battery No. 11, 12. Battery No. 12, 13. Battery, 14. Phase change material, 15. Liquid cooling channel, 16. Coolant inlet, 17. Coolant outlet, 18. Coolant heat capacity, 19. Circuit switch, 20. Contact thermal resistance with the battery, 21. Contact thermal resistance with the outside. Detailed implementation manners

[0041] The present disclosure will be further described below in conjunction with the accompanying drawings and embodiments.

[0042] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further descriptions of the present disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present disclosure belongs.

[0043] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary implementation manners according to the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0044] In the case of no conflict, the embodiments in the present disclosure and the features in the embodiments can be combined with each other.

[0045] Embodiment 1 of the present disclosure introduces a method for thermal management and thermal runaway suppression of power batteries based on a lumped model.

[0046] As Figure 1 shown, a method for thermal management and thermal runaway suppression of power batteries based on a lumped model includes the following steps:

[0047] Construct a thermal management geometric structure for power batteries based on liquid cooling microchannels and phase change materials;

[0048] Obtain the physical property parameters of the thermal management geometric structure and establish a heat generation model for a single battery;

[0049] Construct a lumped model of a power battery based on the heat generation models of multiple single cells;

[0050] Add a thermal runaway propagation suppression management module to the lumped model, predict the temperature change of the power battery based on the lumped model, determine the conditions for the power battery to trigger thermal runaway, and start the liquid-cooled microchannel before reaching the thermal runaway trigger conditions of the power battery to suppress the spread of thermal runaway and achieve thermal management of the power battery.

[0051] As one or more embodiments, the thermal management geometry consists of a liquid-cooled microchannel and a phase change material. The phase change material selects paraffin as the filler. The phase change material is wrapped around each battery. The amount of phase change material wrapped around each battery is 20 g. The liquid-cooled microchannels are arranged along the vertical direction of the battery. The material of the microchannel is an aluminum shell, and water is used as the coolant. The total flow rate around each battery is 10 L / min, as Figure 2 and Figure 3 shown in the thermal management geometry. The battery pack consists of 12 batteries. When the battery is working normally, only the PCM model is used for heat dissipation. When a battery enters the thermal runaway state, the system starts the liquid-cooling module to suppress the spread of battery thermal runaway.

[0052] The liquid-cooled microchannel design is characterized by consisting of multiple small liquid-cooling channels. 12 channels are distributed on both sides of the wide surface of each battery. The distribution method is that 6 channels are evenly distributed on both sides along the wide surface direction between each battery. The liquid-cooling flow direction is the vertical direction.

[0053] As one or more embodiments, establish the heat transfer relationship according to the connection method between the battery and the thermal management system, and determine the thermal parameters of the lumped model according to the heat transfer relationship. The thermal parameters include the heat capacity of the battery, the internal thermal resistance of the battery, the contact thermal resistance between the batteries, the heat capacity of the thermal management material, the contact thermal resistance between the battery and the thermal management material, the convective thermal resistance of the battery, and the convective thermal resistance of the thermal management material.

[0054] Among them, the heat capacity of the battery is determined by the mass and specific heat capacity of the battery. The internal thermal resistance of the battery is determined by the axial thermal conductivity, radial thermal conductivity of the battery, and the geometric dimensions of the battery. The heat capacity of the thermal management material is determined by the mass and specific heat capacity of the thermal management material. The conduction thermal resistance between the batteries is determined by the thermal conductivity and contact area between the batteries. The conduction thermal resistance between the battery and the thermal management material is determined by the thermal conductivity and contact area between the battery and the thermal management material. The convective thermal resistance of the battery is determined by the thermal conductivity and contact area between the battery and the air. The convective thermal resistance of the thermal management material is determined by the thermal conductivity and contact area between the thermal management material and the air.

[0055] The calculation formula for the heat capacity of the battery is:

[0056] C = ρVC p

[0057] Among them, ρ represents the battery density, C p represents the specific heat capacity of the battery, and V represents the volume of the battery.

[0058] The calculation formula for the thermal resistance inside the battery is:

[0059]

[0060] Among them, δ x,y,z represents the thickness in the x, y, and z directions inside the battery, and λ x,y,z represents the thermal conductivity in the x, y, and z directions inside the battery.

[0061] The calculation formula for the conduction thermal resistance between batteries and between the battery and the thermal management material is:

[0062]

[0063] Among them, h c represents the convective heat transfer coefficient between batteries and between the battery and the thermal management material, and A represents the contact area between batteries and between the battery and the thermal management material.

[0064] The calculation formula for the convective thermal resistance of the battery is:

[0065]

[0066] Among them, h cov is the convective heat transfer coefficient between the battery surface and the environment, and A cov represents the contact area between the battery surface and the environment.

[0067] As one or more embodiments, the heat generation power of the single cell consists of the heat generation amount during normal operation of the battery and the heat generation amount during thermal runaway of the battery.

[0068] The heat generation rate during normal operation of the battery is determined by the Bernardi formula, and the expression is as follows:

[0069] Among them, I is the current, U is the battery terminal voltage, U oc is the battery open-circuit voltage, V is the battery volume, dU oc / dT is the battery entropy heat coefficient, and T represents the thermodynamic temperature.

[0070] The heat generation amount during thermal runaway of the battery is measured through a single cell adiabatic thermal runaway experiment. In the adiabatic test environment, the heat generated by the battery is completely absorbed by the battery and causes a temperature rise of △T. When the heat capacity MC p of the battery is known, the heat generation amount △H during thermal runaway in the adiabatic environment can be accurately obtained as △H = MC p△T. The adiabatic thermal runaway model can be fitted according to the heat generation measured in the experiment and the various chemical components of the battery.

[0071] The heat generation power of the chemical reactions of various materials inside the battery can be expressed by a unified formula, that is

[0072]

[0073] Among them, Q x (t) represents the reaction heat generation power of each battery component x, and the subscript x can be SEI, anode, electrolyte, cathode, etc.; c x (t) represents the normalized concentration of the reactants. △H x is the enthalpy of formation of the chemical reaction of the reactant x, that is, the total heat released after the reactant completely reacts.

[0074] The heat generated by the internal short circuit during thermal runaway is

[0075]

[0076] Among them, ΔH e represents the total electrical energy of the battery when the internal short circuit occurs; Δt represents the average time of electrical energy release. In the adiabatic thermal runaway model, Δt is set to 10 seconds.

[0077] Therefore, the heat generation during the thermal runaway of a single battery is:

[0078] Q(t) = Q e (t) + Q x (t)

[0079] As one or more embodiments, a lumped thermal resistance parameter network of the battery is established; a lumped thermal resistance network is established according to the heat transfer relationship between the battery and the thermal management system.

[0080] (1) Battery thermal resistance network during normal operation

[0081] The battery thermal resistance network during normal operation consists of a battery pack and a phase change material module. The thermal resistance network of the power battery is as Figure 4 shown. Heat is transferred through the thermal resistance between adjacent batteries, the external environment and the phase change material module. The phase change material around a single battery is also regarded as a whole and represented by a temperature node. Heat is transferred through the thermal resistance between the battery, the external environment and the phase change material module. Among them, T c represents the temperature of the central battery; T neigh represents the temperature of the adjacent battery; R c represents the contact resistance between the batteries; R h represents the convective resistance between the cell surface and the surrounding environment; R x 、R y, R z represent the conductive resistances in the x, y, and z directions between the battery cell part and the battery surface respectively; R PCM represents the conduction thermal resistance inside the phase change material.

[0082] According to the thermal resistance network, the energy balance equation at the battery node is as follows

[0083]

[0084] where Q represents the heat generation rate during battery thermal runaway. M c and C p,cell represent the mass and specific heat capacity of the battery respectively.

[0085] (2) Battery thermal resistance network with microchannels added

[0086] Taking one section of microchannels as an example, their thermal resistance network structure is as Figure 5 shown. Regarding one section of microchannels as a whole and representing it with a temperature node, heat transfer occurs with adjacent batteries through thermal resistances.

[0087] The energy balance equation of the microchannels is as follows:

[0088]

[0089] where T L represents the temperature of the microchannels; R L represents the contact resistance between the battery and the microchannels.

[0090] Establish a lumped model based on the established battery lumped thermal resistance network

[0091] The model is represented by an equivalent circuit and consists of an equivalent current source, an equivalent thermal resistance, and an equivalent capacitor as Figure 6 shown. In the model, the heat generation power of the battery is represented by the output of the current source, the heat capacity of the battery is represented by a capacitor, the conduction thermal resistance between batteries is represented by a resistor, and the convective thermal resistance between the battery and the air is represented by a resistor.

[0092] Add a thermal management module based on the battery lumped thermal resistance parameter model. In the model, since the phase change material undergoes a phase change from solid to liquid when heated to the melting temperature, the heat capacity is represented by a variable capacitor, and the thermal resistance between the battery and the thermal management material is represented by a resistor; for the liquid cooling module, in order to simulate the effect of the liquid cooling flow in the model, the liquid in one section of microchannels is divided into two parts, and the heat capacity of the whole section of microchannels is represented by two capacitors. Heat dissipation circulation is achieved through the control of the circuit switch to simulate liquid cooling, as Figure 7 shown.

[0093] Start the model, determine whether the battery reaches the thermal runaway condition. If the thermal runaway condition is reached, after starting the liquid cooling module to suppress thermal runaway, observe the spread of thermal runaway and calculate when it drops to a safe temperature.

[0094] The battery reaches the thermal runaway condition when the temperature of the power battery exceeds 150 °C, or the temperature rise rate dT / dt exceeds 1 °C / s, then it is considered that the power battery has a thermal runaway.

[0095] To verify the accuracy of the thermal resistance model, a three-dimensional thermal management model for suppressing the spread of thermal runaway was established using COMSOL. The thermal runaway of the battery was triggered by a needle prick. The thermal management model consists of liquid cooling microchannels and phase change materials. The phase change materials are wrapped around the battery, and the liquid cooling microchannels are arranged along the vertical direction of the battery; the same thermal management model for suppressing the spread of thermal runaway was established using the lumped thermal resistance model of the present invention, and the results of the two models for suppressing the spread of thermal runaway were compared. Figures 8(a) and 8(b) respectively show the temperature changes of the thermal runaway-triggered battery and the adjacent battery. It can be seen that the thermal management system suppresses the spread of thermal runaway, and at the same time, the results of the two models are very close, proving the reliability of the lumped model.

[0096] By comparing the calculation times of the two methods of the COMSOL three-dimensional model and the lumped thermal resistance model, as Figure 9 shown, it can be seen that the calculation speed of the lumped thermal resistance network method of the present invention is significantly faster than that of the COMSOL model, which will greatly improve the prediction efficiency of the thermal runaway process.

[0097] Demonstrate the specific operation of this thermal management system. First, when the battery is working normally, assume that one battery (Battery-1) has a sharp temperature rise due to a needle prick. At this time, the system starts to predict the temperature of each battery of the battery. The simulation results show that after the thermal runaway of Battery-1 occurs, the heat gradually spreads to the adjacent battery, and the thermal runaway of the adjacent battery has been triggered at 410 s. As Figure 10 shown is a schematic diagram of the temperature changes of the thermal runaway-triggered battery (Battery-1) and the adjacent battery (Battery-2). At this time, the system determines that the battery is about to reach the thermal runaway condition and immediately starts the thermal management system to suppress thermal runaway.

[0098] After starting the thermal management system to suppress thermal runaway, the liquid cooling microchannel module also starts to work. At this time, the system starts to predict the temperature of each battery of the battery according to the current cooling situation, and observes the temperature changes of the thermal runaway-triggered battery (Battery-1) and the adjacent battery (Battery-2) of the thermal runaway-triggered battery. As Figure 11 shown, the predicted maximum temperature of the adjacent battery is 83 °C, and the thermal runaway-triggered battery drops below 100 °C after 700 s, and the spread of thermal runaway is well suppressed.

[0099] Even if the situation of multiple battery cells triggering thermal runaway simultaneously occurs, the combination of phase change material and liquid cooling in this model can also well suppress this extreme situation. Suppose two battery cells (Battery-1, 7) trigger thermal runaway, and the temperature changes of the battery cell triggering thermal runaway (Battery-1) and the adjacent battery cells of the battery cell triggering thermal runaway (Battery-2, 3, 4) are observed. As Figure 12 shown, the adjacent battery cells do not trigger thermal runaway, and after 900 s, the battery cell triggering thermal runaway drops below 100 °C, proving the good effect of this thermal management system in suppressing the spread of thermal runaway.

[0100] The above are only the preferred embodiments of the present disclosure and are not used to limit the present disclosure. For those skilled in the art, various changes and modifications can be made to the present disclosure. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included within the protection scope of the present disclosure.

Claims

1. A method for thermal management and thermal runaway suppression of power batteries based on a lumped model, characterized in that The steps include: Construct the thermal management geometric structure of the power battery based on the liquid-cooled microchannel and phase change material; during the process of constructing the thermal management geometric structure of the power battery, wrap the phase change material around each single battery, and arrange the liquid-cooled microchannels in the vertical direction of the single battery; the liquid-cooled microchannels are designed to be composed of multiple small liquid-cooled channels, with 12 channels distributed on both sides of the wide surface of each battery cell, and the distribution method is that 6 channels are evenly distributed on both sides along the wide surface direction between each battery cell, and the liquid-cooled flow direction is the vertical direction; Obtain the physical property parameters of the thermal management geometric structure and construct the lumped model of the power battery; the physical property parameters of the thermal management geometric structure include the heat capacity of the single battery, the thermal resistance of the single battery, the contact thermal resistance between single batteries, the heat capacity of the thermal management material, the contact thermal resistance between the single battery and the thermal management material, the convective thermal resistance of the single battery, and the convective thermal resistance of the thermal management material; during the process of constructing the lumped model of the power battery, establish the lumped thermal resistance network of the power battery based on the established single battery heat generation model and physical property parameters, and establish the lumped thermal resistance model of the power battery by combining with the equivalent circuit; The lumped thermal resistance network of the power battery includes the battery thermal resistance network when the power battery operates normally and the power battery thermal resistance network with microchannels; The battery thermal resistance network under normal operation consists of a battery pack and a phase change material module, and heat transfer occurs between adjacent batteries, the external environment, and the phase change material module through thermal resistance. Regarding the phase change material around a single battery as a whole, it is represented by a temperature node; among them, T c represents the temperature of the central battery; T neigh represents the temperature of the adjacent battery; R c represents the contact resistance between batteries; R h represents the convective resistance between the cell surface and the surrounding environment; R x 、R y 、R z represent the conductive resistances in the x, y, and z directions between the battery core part and the battery surface respectively; R PCM represents the conduction thermal resistance inside the phase change material; According to the thermal resistance network, the energy balance equation at the battery node is as follows: Among them, Q represents the heat generation rate during battery thermal runaway; M c and C p,cell represent the mass and specific heat capacity of the battery, respectively; The power battery thermal resistance network with microchannels regards one section of microchannels as a whole, represents it with a temperature node, and transfers heat to adjacent batteries through thermal resistance; The energy balance equation of the microchannel is as follows: Among them, T L represents the temperature of the microchannel; R L represents the contact resistance between the battery and the microchannel; Add a thermal runaway spread suppression management module to the lumped model, predict the temperature change of the power battery based on the lumped model, determine the conditions for the power battery to trigger thermal runaway, start the liquid-cooled microchannels before reaching the thermal runaway trigger conditions of the power battery, suppress the spread of thermal runaway, and realize the thermal management of the power battery.

2. The method for thermal management and thermal propagation suppression of a power battery based on a lumped model according to claim 1, characterized in that, When the single battery operates normally, the phase change material is used for heat dissipation in the thermal management geometric structure; when the single battery enters the thermal runaway state, the liquid-cooled microchannels are started for heat dissipation in the thermal management geometric structure to suppress the spread of thermal runaway of the power battery.

3. A method for thermal management and thermal propagation suppression of a power battery based on a lumped model as described in claim 1, characterized in that, The single battery heat generation model includes the heat generation amount when the single battery operates normally and the heat generation amount when the single battery undergoes thermal runaway.

4. The method for thermal management and thermal propagation suppression of a power battery based on a lumped model as described in claim 1, characterized in that, The lumped model is represented by an equivalent circuit composed of an equivalent current source, an equivalent resistance, and an equivalent capacitance; among them, the output of the equivalent current source represents the single battery heat generation model; the equivalent capacitance represents the heat capacity of the single battery; the equivalent resistance represents the thermal resistance.

5. A method for thermal management and thermal propagation suppression of a power battery based on a lumped model, as described in claim 4, characterized in that The thermal runaway spread suppression management module includes a phase change material module and a liquid-cooled module; regard the phase change material module around the single battery as a whole, and when the phase change material is heated to the melting temperature, the phase change material undergoes a phase change from solid to liquid.

6. The method for thermal management and thermal propagation suppression of a power battery based on a lumped model as described in claim 1, wherein When determining the conditions for the power battery to trigger thermal runaway, when the temperature of the power battery exceeds the preset thermal runaway temperature value or the temperature rise rate of the power battery exceeds the preset thermal runaway temperature rise rate value, the power battery undergoes thermal runaway.

Images