CN114757038A - Power battery thermal diffusion simulation method based on electric-thermal coupling - Google Patents

Power battery thermal diffusion simulation method based on electric-thermal coupling Download PDF

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CN114757038A
CN114757038A CN202210421684.7A CN202210421684A CN114757038A CN 114757038 A CN114757038 A CN 114757038A CN 202210421684 A CN202210421684 A CN 202210421684A CN 114757038 A CN114757038 A CN 114757038A
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邝男男
栗国
赵光磊
郝剑虹
崔东
孟宪明
胡帛涛
季中豪
尤楠
曹欢
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China Automotive Technology and Research Center Co Ltd
CATARC Tianjin Automotive Engineering Research Institute Co Ltd
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CATARC Tianjin Automotive Engineering Research Institute Co Ltd
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Abstract

The invention provides a power battery thermal diffusion simulation method based on electrothermal coupling, which is a working flow for simulating discharge behavior in the thermal diffusion process of a power battery system and mainly comprises the following steps: establishing an equivalent circuit model of the power battery system; establishing a power battery system heat transfer model; establishing a thermal runaway diffusion model of the power battery system; the equivalent circuit model is coupled with a thermal runaway diffusion model and a thermal generation model, respectively. The power battery thermal diffusion simulation method based on the electrothermal coupling can simultaneously analyze the discharge behavior and the reaction heat generation behavior of the power battery in the thermal runaway process, realize the electrothermal coupling of the battery in the thermal runaway process, greatly improve the simulation precision of a battery thermal diffusion model, optimize the safety of a power battery system based on the simulation result and improve the safety of a new energy automobile.

Description

Power battery thermal diffusion simulation method based on electric-thermal coupling
Technical Field
The invention belongs to the field of new energy automobile safety, and particularly relates to a power battery thermal diffusion simulation method based on electric-thermal coupling.
Background
The lithium ion battery has the characteristics of high energy density, low self-discharge rate, long service life and the like, so that the lithium ion battery is widely applied as a power source of a new energy automobile. The lithium ion battery has instability, so that the power battery is easy to generate a thermal runaway condition under an abuse working condition, and a battery pack causes thermal diffusion to cause ignition and combustion of a new energy vehicle. In order to improve the safety of new energy automobiles, various major research institutions have conducted very intensive research on thermal runaway and thermal diffusion of power batteries. At present, most of research aiming at battery thermal runaway, particularly thermal diffusion, takes electric energy released by short circuit in the battery and energy released by chemical reaction among component materials as objects, analyzes the heat generation rate of the battery, and ignores heat generated by other batteries discharging the battery when the battery is in thermal runaway. Therefore, in order to improve the simulation accuracy of the thermal diffusion model of the power battery, optimize the safety protection performance of the battery system and further improve the safety of the new energy automobile, it is necessary to develop a thermal diffusion simulation method of the power battery based on the electrothermal coupling.
The invention provides a thermal diffusion simulation method for a power battery based on electrothermal coupling, which aims to simultaneously analyze thermal runaway of the power battery and influence of a discharge phenomenon and a chemical reaction heat generation phenomenon on thermal diffusion in a thermal diffusion process and realize electrothermal coupling in the thermal diffusion process of the battery. The method is characterized in that a power battery equivalent circuit model and a thermal runaway model are set up, wherein the equivalent circuit model simulates a discharging behavior of the power battery in a thermal runaway process, the thermal runaway model simulates a thermogenic behavior of a chemical reaction of the power battery in the thermal runaway process, the coupling of the two models can simultaneously analyze the discharging behavior and the thermogenic behavior of the reaction of the battery in the thermal runaway process, the simulation precision of the thermal runaway and thermal diffusion models is greatly improved, and a technical basis is further provided for improving the safety of a power battery system.
Disclosure of Invention
In view of the above, the present invention is directed to provide a thermal diffusion simulation method for a power battery based on electrothermal coupling, so as to solve the problem of analyzing thermal runaway of the power battery and the influence of a discharge phenomenon and a chemical reaction heat generation phenomenon on thermal diffusion in a thermal diffusion process simultaneously, and achieving electrothermal coupling in the thermal diffusion process of the battery.
In order to achieve the purpose, the technical scheme of the invention is realized as follows:
A power battery thermal diffusion simulation method based on electric-thermal coupling comprises the following steps:
s1, establishing a battery equivalent circuit model according to a battery voltage module calculation formula and the state of charge of the battery;
s2, establishing a power battery heat transfer model according to a battery heat transfer model formula, giving the heat generation quantity of a battery in the circuit model to the heat transfer model, giving the battery temperature in the heat transfer model to the circuit model, and coupling the equivalent circuit model with the heat transfer model;
s3, establishing a thermal runaway model of the power battery according to a heat generation formula, giving the heat generation quantity in the thermal runaway model to a heat transfer model, giving the battery temperature of the heat transfer model to the thermal runaway model, and coupling the thermal runaway model with the heat transfer model;
and S4, based on the coupling of the equivalent circuit model and the heat transfer model in S2 and the coupling of the thermal runaway model and the heat transfer model in S3, the electric-thermal coupling of thermal runaway and thermal diffusion of the power battery is realized.
Further, the equivalent circuit model in step S1 includes: the battery voltage module is an equivalent resistance module for connecting the internal resistance of the battery and the battery with the pole piece;
the voltage calculation formula of the battery voltage module is as follows:
Figure BDA0003608071710000021
in the above formula, Eocv(SOC, T) represents the open circuit voltage of the battery under different SOC and temperature conditions, E ocv,ref(SOC) represents the open circuit voltage of the battery under different SOC conditions,
Figure BDA0003608071710000034
temperature derivative of open circuit voltage, T represents battery temperature, TrefRepresents a reference temperature;
the state of charge of the battery is calculated by an ampere-hour integration method and is shown as the following formula:
Figure BDA0003608071710000031
in the above equation, SOC represents the current state of charge of the battery, SOC0Representing the initial state of charge of the battery, I representing the current, CNRepresents the capacity of the battery;
and (3) setting the internal resistance of the battery and the equivalent resistance of a battery connection pole piece as R, and solving a current I according to the ohm law, wherein the formula of the current I is as follows: i ═ Eocv(SOC,T)/R；
Substituting the current I into the SOC formula of the battery to obtain the SOC of the power battery under the current working condition, substituting the SOC of the power battery into the voltage module calculation formula to obtain the open-circuit voltage E of the battery under the conditions of the current SOC and the temperature Tocv(SOC, T), the loop is iterated in turn until the battery SOC equals 0.
Further, the battery heat transfer model formula in step S2 is as follows:
Figure BDA0003608071710000032
in the above formula, ρ represents the average density of the battery, CpRepresents the average specific heat capacity of the battery, dT/dT represents the temperature rise rate of the battery, rho Cp(dT/dT) is the net heat generation power of the cell; qgenRepresenting heat-generating power, QdisRepresenting the heat dissipation power; λ x, λ y, λ z represent the thermal conductivity of the cell in the x, y, z directions, respectively;
Figure BDA0003608071710000033
Representing the temperature gradient of the cell in the x, y, z directions, respectively.
Further, the coupling process of the equivalent circuit model and the heat transfer model is as follows:
let the internal resistance of the battery be r, then according to Joule's law Qe＝I2R Heat generation power Q for obtaining internal resistance of batteryeInternal resistance of the battery to generate heat power QeThe real-time temperature T of the battery is obtained by being substituted into a battery heat transfer model formula, and the temperature T is substituted into a battery voltage calculation formula to obtain the open-circuit voltage E of the battery at the current temperatureocv(SOC, T), the power cell equivalent circuit is coupled with the heat transfer model.
Further, in step S3, according to the situation that the power battery may have chemical side reactions during thermal runaway: the method comprises the following steps of SEI film decomposition, cathode material and electrolyte reaction, diaphragm decomposition, anode material decomposition and electrolyte decomposition to obtain a heat generation formula:
Figure BDA0003608071710000041
in the above formula, x represents SEI film, negative electrode material, diaphragm, electrolyte, positive electrode material, and QxDenotes the heat generation power, Δ H, of each materialxDenotes the reaction formation enthalpy of each reaction, mxDenotes the respective material masses, RxDenotes the reaction rate, cxDenotes the normalized concentration of each material, AxIndicating the pre-factor of the reaction of the respective materials, ExDenotes the activation energy of each material, n and a denote the reaction order (generally, n is 1, a is 0), and T denotes xThe real-time temperature of each material reaction is shown, g (x) is a correction coefficient, QxThermal runaway generates thermal power.
Further, the process of coupling the thermal runaway model with the heat transfer model in step S3 is as follows:
generating power Q by thermal runawayxAnd substituting the real-time temperature T into a heat generation formula in the thermal runaway process to obtain the reaction rate of the component material at the current temperature, and coupling the thermal runaway model with the heat transfer model.
Compared with the prior art, the power battery thermal diffusion simulation method based on the electrothermal coupling has the following advantages:
(1) according to the power battery thermal diffusion simulation method based on electrothermal coupling, the thermal diffusion model and the circuit model are coupled, the discharge phenomenon of the power battery in the thermal diffusion process can be analyzed, the influence of current and SOC on the thermal diffusion of the battery can be analyzed based on the discharge phenomenon, and the thermal runaway and the simulation precision of the thermal diffusion model are improved.
(2) According to the power battery thermal diffusion simulation method based on electrothermal coupling, the heat generation power of the battery connecting pole piece can be obtained according to the numerical calculation result, and based on the characteristic that the connecting pole piece is fused when reaching a certain temperature, a proper material is selected as the connecting pole piece, so that the heat generation power in the thermal diffusion process of the battery is reduced, the thermal diffusion hazard is reduced, and the safety of the power battery system is improved.
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The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 is a flowchart of a thermal diffusion simulation method for a power battery based on electrothermal coupling according to an embodiment of the present invention;
fig. 2 is a schematic diagram of an equivalent circuit model of a power battery according to an embodiment of the invention;
fig. 3 is a first schematic view of a power battery small module according to an embodiment of the present invention;
fig. 4 is a second schematic diagram of a power battery small module model according to an embodiment of the invention;
FIG. 5 is a schematic diagram illustrating a thermal runaway temperature change of a battery according to an embodiment of the invention;
FIG. 6 is a schematic diagram illustrating the variation of SOC of a battery according to an embodiment of the present invention;
fig. 7 is a cloud diagram of a temperature distribution of a battery at a time of thermal runaway according to an embodiment of the invention.
Description of reference numerals:
1-cell I, 2-cell II, 3-cell III, 4-cell IV, 5-heating plate, 6-first group of connecting pole pieces, 7-second group of connecting pole pieces and 8-third group of connecting pole pieces.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art through specific situations.
The present invention will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
As shown in fig. 1, a workflow for simulating a discharging behavior in a thermal diffusion process of a power battery system mainly includes: 1) establishing an equivalent circuit model of the power battery system; 2) establishing a heat transfer model of the power battery system; 3) establishing a thermal runaway diffusion model of the power battery system; the equivalent circuit model is coupled with a thermal runaway diffusion model and a thermogenic model, respectively.
1) And establishing a power battery equivalent circuit model according to the battery system, wherein the equivalent circuit model comprises a battery voltage module, a battery internal resistance module and an equivalent resistance module of a battery connecting pole piece. The battery voltage calculation formula of the battery equivalent circuit model is shown as the following formula:
Figure BDA0003608071710000061
in the above formula, Eocv(SOC, T) represents the open circuit voltage of the battery under different SOC and temperature conditions, Eocv,ref(SOC) represents the open circuit voltage of the battery under different SOC conditions,
Figure BDA0003608071710000074
representing the temperature derivative of the open circuit voltage, T representing the battery temperature, TrefIndicating the reference temperature.
The SOC of the battery is calculated by an ampere-hour integration method and is shown as the following formula:
Figure BDA0003608071710000071
in the above equation, SOC represents the current state of charge of the battery, SOC0Representing the initial state of charge of the battery, I representing the current, C NIndicating the capacity of the battery.
Specifically, let the equivalent resistance in the battery be R, then the value obtained by ohm's law I ═ Eocv(SOC, T)/R can be used for calculating the current I in the equivalent circuit model, the current I is substituted into the formula (2), and the SOC of the power battery under the current working condition can be calculated; the calculated SOC is substituted into the formula (1), and the open-circuit voltage E of the battery under the conditions of the current SOC and the temperature T can be obtainedocv(SOC, T), based on which loop iterations of the equivalent circuit model are implemented until the battery SOC equals 0.
2) Establishing a power battery heat transfer model, wherein the basic equation of the heat transfer model is shown as the following formula:
Figure BDA0003608071710000072
in the above formula, ρ represents the average density of the battery, CpRepresents the average specific heat capacity of the battery, dT/dT represents the temperature rise rate of the battery, rho Cp(dT/dT) is the net heat generation power of the cell; qgenRepresenting heat-generating power, QdisRepresenting the heat dissipation power; λ x, λ y, λ z represent the thermal conductivity of the cell in the x, y, z directions, respectively;
Figure BDA0003608071710000073
representing the temperature gradient of the cell in the x, y, z directions, respectively.
Specifically, let the internal resistance of the battery be r, then Q is determined according to Joule's lawe＝I2R the heat generation power of the internal resistance of the battery can be obtained. Resistance of battery to heat power QeIn the formula (3), the real-time temperature T of the battery can be obtained, and the battery at the current temperature can be obtained by substituting the temperature T in the formula (1) Open circuit voltage E ofocv(SOC, T). Based on this, the coupling of power battery equivalent circuit model and heat transfer model has been realized.
3) And establishing a thermal runaway heat production model of the power battery according to a thermal runaway heat production mechanism of the power battery. The power battery can generate chemical side reactions in the thermal runaway process: the method comprises the steps of SEI film decomposition, negative electrode material and electrolyte reaction, diaphragm decomposition, positive electrode material decomposition and electrolyte decomposition. The heat generation formula is as follows:
Figure BDA0003608071710000081
in the above formula, x represents SEI film, negative electrode material, diaphragm, electrolyte, positive electrode material, and QxDenotes the heat generation power, Δ H, of each materialxDenotes the reaction formation enthalpy of each reaction, mxDenotes the respective material masses, RxDenotes the reaction rate, cxDenotes the normalized concentration of each material, AxIndicating the pre-factor of the reaction of the respective materials, ExDenotes the activation energy of each material, n and a denote the reaction order (generally, n is 1, a is 0), and T denotesxRepresenting the real-time temperature of the reaction of each material, g (x) being the correction factor, QxFor thermal runaway thermogenic power, QxEndowing the power battery with a heat generation model, namely, simulating the heat generation behavior of the power battery in the thermal runaway process.
Specifically, the thermal runaway heat generation rate Q calculated in the formula (4)xIn formula (3), the real-time temperature T of the power battery in the thermal runaway process can be obtained, and in formula (4), the reaction rate of the component material at the current temperature can be obtained. And coupling the power battery heat transfer model and the thermal runaway model based on the method.
According to the battery equivalent circuit model shown in the formula (1) and the formula (2), the battery heat transfer model shown in the formula (3) and the battery thermal runaway model shown in the formula (4), the electric-thermal coupling of the thermal runaway and the thermal diffusion of the power battery is realized.
The specific embodiment is as follows:
fig. 2 is a schematic diagram of an equivalent circuit of the small power battery module, and fig. 3 is a schematic diagram of the small power battery module. V1-V4 in fig. 2 represent 4 dc voltage sources, which respectively represent voltages of 4 cells in fig. 3; in fig. 2, R1, R2, R3, and R4 represent 4 resistors, which respectively represent the internal resistances of the 4 battery cells in fig. 3; resistors R5 and R8 in FIG. 2 represent the resistances of the first set of connected pole pieces in FIG. 3; resistors R6 and R9 in FIG. 2 represent the resistances of the second set of connected pole pieces in FIG. 3; resistors R7 and R10 in fig. 2 represent the resistances of the third set of connected pole pieces in fig. 3.
When 4 electric cores are parallelly connected, the electric potential equals everywhere, can not take place the phenomenon of discharging in the module. When the heating sheet in fig. 3 starts to heat the cell, the temperature of the first cell rises, and when the temperature of the first cell exceeds the safety boundary, the cell generates thermal runaway, at this time, the internal resistance of the first cell rises, the voltage suddenly drops, and a large amount of heat is generated, so that the temperature further rises.
When the battery cell generates thermal runaway, the equivalent circuit model shown in fig. 2 changes correspondingly, the voltage source V1 becomes 0, and the internal resistance R1 of the battery cell i increases. Because the branch where the voltage source V1 is not under voltage, the voltage sources V2, V3, and V4 all discharge to the voltage source V1, that is, the second cell, the third cell, and the fourth cell in fig. 3 all discharge to the first cell, at this time, the temperatures of the first cell, the second cell, the third cell, and the fourth cell all rise, and the heat of the first cell is divided into two parts, one part is heat generated by the thermal runaway of the first cell itself, and the other part is heat generated by the flow of current.
Wherein the heat generated by the battery core under thermal runaway is shown as the following formula,
Figure BDA0003608071710000091
in the above formula, x represents SEI film, negative electrode material, separator, electrolyte, positive electrode material, QxDenotes the heat generation power, Δ H, of each materialxDenotes the reaction formation enthalpy, m, of each reactionxDenotes the respective material masses, RxDenotes the reaction rate, cxDenotes the normalized concentration of each material, AxIndicating the pre-factor of the reaction of the respective materials, ExIndicates the activation energy, T, of each materialxThe real-time temperature of each material reaction is shown, g (x) is a correction coefficient, and x represents SEI, a negative electrode, a diaphragm, a positive electrode and electrolyte. Will QxAnd giving the first battery cell, namely obtaining the heat generation amount in the thermal runaway process of the first battery cell.
The heat generated by the first battery cell due to the flowing of the current is I according to Joule's law Q2R is calculated, where I is the current flowing through the cell-internal resistance R1, and R is the resistance of the cell after the internal short circuit occurs, and the resistance is greater than the battery internal resistance R1. And Q is given to the first battery cell, so that the heat generated by the first battery cell due to the flowing of the current can be obtained.
When the second battery cell, the third battery cell and the first battery cell are discharged, the open-circuit voltage of the first battery cell is reduced along with the reduction of the SOC. The change of SOC is calculated by ampere-hour integration method as shown in the following formula,
Figure BDA0003608071710000101
in the above equation, SOC xIndicate SOC and SOC of cell two, cell three and cell fourx,0Represents the initial SOC, I of the second, third and fourth cellsxIndicates the current flowing through cell two, cell three and cell four, CNIndicating the capacity of the cell. The real-time SOC of the second battery cell, the third battery cell and the fourth battery cell can be calculated through the formula.
After the SOC of each battery cell is calculated, the open-circuit voltage of each battery cell is obtained according to the corresponding relation between the open-circuit voltage and the SOC, as shown in the following formula,
Figure BDA0003608071710000102
in the above formula, Eocv，x(SOCx,Tx) Indicating the open-circuit voltages of the second cell, the third cell and the fourth cell under different SOC and temperature conditions, Eocv,ref,x(SOCx) Indicating the open circuit voltages of the second cell, the third cell and the fourth cell under different SOC conditions,
Figure BDA0003608071710000103
indicating the open-circuit voltage temperature derivatives, T, of cell two, cell three, and cell fourxTemperature, T, of cell two, cell three, and cell fourref，xIndicating the cell reference temperature. The open-circuit voltages of the second battery cell, the third battery cell and the fourth battery cell can be calculated through the formula.
When the thermal runaway of the first battery cell is finished, the branch of the power supply 1 in the equivalent circuit model shown in fig. 2 is open, and the internal resistance value is infinite. And when the temperature of the second battery cell reaches the thermal runaway trigger temperature, discharging the third battery cell and the second battery cell in the four directions, and repeating the calculation process in the whole simulation. Fig. 5 is a temperature change of 4 cells, fig. 6 is a SOC change of a second cell, a third cell, and a fourth cell, and fig. 7 is a cloud diagram of a temperature distribution of the battery module at a certain time.
In addition, the invention can not only research the discharge behavior of the power battery in the thermal runaway process, but also research the influence of the fusing characteristic of the battery module connected with the pole piece on the thermal runaway diffusion.
Specifically, assuming that the fusing temperature of the module connection pole piece is 200 ℃, when the temperature of the first group of connection pole pieces in the battery heat transfer model shown in fig. 3 and 4 exceeds 200 ℃, the resistance values of the resistors R5 and R8 in fig. 2 become infinite, and then the simulation of fusing of the connection pole pieces is realized. According to the simulation result of the working condition, the influence of the fusing characteristic of the connecting pole piece on the thermal diffusion of the power battery can be analyzed.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and should not be taken as limiting the scope of the present invention, which is intended to cover any modifications, equivalents, improvements, etc. within the spirit and scope of the present invention.

Claims (6)

1. A power battery thermal diffusion simulation method based on electric-thermal coupling is characterized by comprising the following steps:
s1, establishing a battery equivalent circuit model according to a battery voltage module calculation formula and the state of charge of the battery;
s2, establishing a power battery heat transfer model according to a battery heat transfer model formula, giving the heat generation quantity of the battery in the circuit model to the heat transfer model, giving the battery temperature in the heat transfer model to the circuit model, and coupling the equivalent circuit model with the heat transfer model;
S3, establishing a thermal runaway model of the power battery according to a heat generation formula, giving the heat generation quantity in the thermal runaway model to a heat transfer model, giving the battery temperature of the heat transfer model to the thermal runaway model, and coupling the thermal runaway model with the heat transfer model;
and S4, based on the coupling of the equivalent circuit model and the heat transfer model in S2 and the coupling of the thermal runaway model and the heat transfer model in S3, the electric-thermal coupling of thermal runaway and thermal diffusion of the power battery is realized.
2. The method for simulating thermal diffusion of a power battery based on electrothermal coupling according to claim 1, wherein the equivalent circuit model in step S1 includes: the battery voltage module is an equivalent resistance module for connecting the internal resistance of the battery and the battery with the pole piece;
the voltage calculation formula of the battery voltage module is as follows:
Figure FDA0003608071700000011
in the above formula, Eocv(SOC, T) represents the open circuit voltage of the battery under different SOC and temperature conditions, Eocv,ref(SOC) represents the open circuit voltage of the battery under different SOC conditions,
Figure FDA0003608071700000012
representing the temperature derivative of the open circuit voltage, T representing the battery temperature, TrefRepresents a reference temperature;
the state of charge of the battery is calculated by an ampere-hour integration method and is shown as the following formula:
Figure FDA0003608071700000021
in the above equation, SOC represents the current state of charge of the battery, SOC0Denotes the beginning of the cell Initial state of charge, I represents current, CNRepresents the capacity of the battery;
and (3) setting the internal resistance of the battery and the equivalent resistance of a battery connection pole piece as R, and solving a current I according to the ohm law, wherein the formula of the current I is as follows: I-Eocv(SOC,T)/R；
Substituting the current I into the SOC formula of the battery to obtain the SOC of the power battery under the current working condition, substituting the SOC of the power battery into the voltage module calculation formula to obtain the open-circuit voltage E of the battery under the conditions of the current SOC and the temperature Tocv(SOC, T), the loop is iterated in turn until the battery SOC equals 0.
3. The method for simulating the thermal diffusion of the power battery based on the electrothermal coupling according to claim 1, wherein the battery heat transfer model formula in step S2 is as follows:
Figure FDA0003608071700000022
in the above formula, ρ represents the average density of the battery, CpRepresents the average specific heat capacity of the battery, dT/dT represents the temperature rise rate of the battery, rho Cp(dT/dT) is the net heat generation power of the cell; qgenRepresenting heat generation power, QdisRepresenting the heat dissipation power; λ x, λ y, λ z represent the thermal conductivity of the cell in the x, y, z directions, respectively;
Figure FDA0003608071700000023
representing the temperature gradient of the cell in the x, y, z directions, respectively.
4. The method for simulating the thermal diffusion of the power battery based on the electrothermal coupling is characterized in that the coupling process of the equivalent circuit model and the heat transfer model is as follows:
Let the internal resistance of the battery be r, then according to Joule's law Qe＝I2R Heat generation power Q for obtaining internal resistance of batteryeInternal resistance of the battery to generate heat power QeHeat transfer model male with batteryIn the formula, the real-time temperature T of the battery is obtained, the temperature T is substituted into a battery voltage calculation formula, and the open-circuit voltage E of the battery at the current temperature is obtainedocv(SOC, T), the power cell equivalent circuit is coupled with the heat transfer model.
5. The method for simulating thermal diffusion of the power battery based on the electrothermal coupling of claim 1, wherein in step S3, according to the fact that the power battery may have chemical side reactions during thermal runaway: the method comprises the following steps of SEI film decomposition, cathode material and electrolyte reaction, diaphragm decomposition, anode material decomposition and electrolyte decomposition to obtain a heat generation formula:
Figure FDA0003608071700000031
in the above formula, x represents SEI film, negative electrode material, diaphragm, electrolyte, positive electrode material, and QxDenotes the heat generation power, Δ H, of each materialxDenotes the reaction formation enthalpy of each reaction, mxDenotes the respective material masses, RxDenotes the reaction rate, cxDenotes the normalized concentration of each material, AxIndicating the pre-factor of the reaction of the respective materials, ExDenotes the activation energy of each material, n, a denote the reaction order, TxRepresenting the real-time temperature of the reaction of each material, g (x) being the correction factor, Q xThermal runaway generates thermal power.
6. The electric-thermal coupling-based thermal diffusion simulation method for the power battery as claimed in claim 5, wherein the thermal runaway model and the heat transfer model in step S3 are coupled as follows:
generating heat Q by thermal runawayxAnd substituting the real-time temperature T into a heat generation formula in the thermal runaway process to obtain the reaction rate of the component material at the current temperature, and coupling the thermal runaway model with the heat transfer model.
CN202210421684.7A 2022-04-21 2022-04-21 Power battery thermal diffusion simulation method based on electric-thermal coupling Pending CN114757038A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
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CN115447389A (en) * 2022-09-02 2022-12-09 中国第一汽车股份有限公司 Battery safety monitoring system, battery assembly and electric vehicle
CN116127688A (en) * 2022-10-09 2023-05-16 吉林大学 Full life cycle thermoelectric coupling modeling method for battery module
CN116562107A (en) * 2023-07-06 2023-08-08 中汽研（天津）汽车工程研究院有限公司 Power battery system thermal diffusion simulation method, device and medium

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115447389A (en) * 2022-09-02 2022-12-09 中国第一汽车股份有限公司 Battery safety monitoring system, battery assembly and electric vehicle
CN116127688A (en) * 2022-10-09 2023-05-16 吉林大学 Full life cycle thermoelectric coupling modeling method for battery module
CN116127688B (en) * 2022-10-09 2024-01-02 吉林大学 Full life cycle thermoelectric coupling modeling method for battery module
CN116562107A (en) * 2023-07-06 2023-08-08 中汽研（天津）汽车工程研究院有限公司 Power battery system thermal diffusion simulation method, device and medium
CN116562107B (en) * 2023-07-06 2023-09-05 中汽研（天津）汽车工程研究院有限公司 Power battery system thermal diffusion simulation method, device and medium

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