Composite heating method and system for power battery pack
By setting a heating film on the surface of the power battery pack and establishing a composite heating system model, the problem of poor performance of lithium-ion power batteries at low temperatures is solved, rapid heating and efficient endurance are achieved, and power consumption is reduced.
Patent Information
- Application Number
- CN202510856939.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-25
- Publication Date
- 2025-09-26
AI Technical Summary
Under low temperature conditions, the available power and energy of lithium-ion batteries are significantly reduced, resulting in poor power performance and reduced driving range of electric vehicles. Existing heating methods are inefficient or harmful to battery life.
A heating film is set on the surface of the power battery pack and connected in series with the battery to establish an internal and external composite heating system model. The heating process is controlled by changing the resistance value of the heating film, and rapid heating is achieved by combining internal and external heat generation.
Restore the battery's normal temperature discharge capacity in a short time, improve the vehicle's power and low-temperature endurance, reduce low-temperature mileage attenuation, and reduce power consumption.
Smart Images
Figure CN120709587A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of battery technology, and in particular to a composite heating method and system for a power battery pack. Background Art
[0002] Generally, at low temperatures, the conduction rate of lithium ions slows, significantly reducing the available power and energy of power batteries. Furthermore, lithium plating forms on the anode surface, accelerating lifespan degradation and increasing the risk of battery life. This directly leads to poor power performance and significantly reduced driving range in electric vehicles, seriously impacting their use in all climates.
[0003] Currently, there are two main heating methods for lithium-ion power batteries: external heating and internal heating. External heating is less efficient and results in greater temperature inconsistency in the battery. Internal heating, on the other hand, has a more complex control mechanism for the preheating process, which can adversely affect the battery's cycle life and potentially lead to thermal runaway. Furthermore, the vehicle's power is poor, and its range is limited under low-temperature conditions. Summary of the Invention
[0004] The purpose of this application is to provide a composite heating method, system, electronic device and computer-readable storage medium for a power battery pack, which can achieve the technical effects of improving the power of the entire vehicle, increasing the low-temperature cruising range and reducing the low-temperature mileage attenuation.
[0005] In a first aspect, the present application provides a composite heating method for a power battery pack, comprising: Establishing a model of a combined internal and external heating system for a power battery pack, wherein the power battery pack includes a plurality of power batteries, each of which has a heating film disposed on its surface, and the heating film is connected in series with the power battery; Obtaining an objective function that follows the change in the resistance value of the heating film according to the heating system model; Preprocessing the objective function to obtain a preprocessed objective function; Obtaining resistance target data of the heating film according to the heating target bias and the preprocessed target function; The composite heating of the power battery pack is controlled according to the resistance target data.
[0006] In the above implementation process, a heating film is provided on the surface of the power battery, and the heating film and the power battery are connected in series; thereby, a composite internal and external heating system model of the power battery pack is established, and the resistance target data of the heating film is obtained according to the heating system model, and then the composite heating process of the power battery pack is controlled by the resistance target data; the composite heating method of the power battery pack performs composite heating on the power battery itself through the joint heat generation of the power battery and the metal film, and combines the advantages of internal heating to enable the battery in an extremely low temperature environment to recover to normal temperature discharge capacity in a relatively short time, effectively solving the weak pain points of low-temperature automobile power and improving the power of the whole vehicle; in addition, the composite heating method comprehensively considers the low-temperature battery power attenuation and the battery heating energy consumption, consumes less power, can restore the available energy of the battery, and effectively improves the low-temperature cruising range; therefore, the composite heating method of the power battery pack can achieve the technical effects of improving the power of the whole vehicle, improving the low-temperature cruising range, and reducing the attenuation of low-temperature mileage.
[0007] Furthermore, the steps of establishing a combined internal and external heating system model of the power battery pack include: Establishing an equivalent circuit model according to the voltage of the power battery, the battery state of charge, the average temperature of the battery surface and the resistance value of the heating film; Establishing a heat generation model based on battery mass, battery specific heat capacity, internal heat generation of the power battery, and external heat generation of the heating film; Establishing an electrothermal coupling model based on a heat conduction model between the heating film and the power battery; An internal and external composite heating system model of a power battery pack is established based on the equivalent circuit model, the heat generation model, and the electrothermal coupling model.
[0008] In the above implementation process, the equivalent circuit model can be used to describe the changes in the electrical characteristic parameters of the power battery during low-temperature heating, and the heat generation model can be used to characterize the energy transfer process between the power battery and the heating film during the heating process. Combined with the electrothermal coupling model, a composite internal and external heating system model of the power battery pack is established, which can be used to accurately describe the heating process of the power battery-heating film, and thus realize the control of the composite heating process of the power battery.
[0009] Furthermore, before the step of establishing an electrothermal coupling model according to the heat conduction model between the heating film and the power battery, the method further includes: Dividing the power battery into multiple equal parts along the length direction to obtain a battery multi-division model; Establishing an internal heat conduction model of the power battery according to the heat capacity, heat generation rate and thermal resistance of the power battery; A heat conduction model between the power batteries is established according to the heat source, heat capacity, thermal resistance of the heating film and the internal heat conduction model of the power battery.
[0010] In the above implementation process, considering the large inconsistency of the internal temperature changes of the power battery, the power battery is divided into multiple equal parts along the length direction to accurately calculate the temperature of each part of the power battery; combined with the heat source, heat capacity, and thermal resistance of the heating film, the heat conduction of the heating film to the battery can be accurately calculated, and a heat conduction model between the power batteries can be established.
[0011] Furthermore, the step of obtaining an objective function that follows the change of the resistance value of the heating film according to the heating system model includes: determining design variables according to the resistance value of the heating film before heating; Obtaining a plurality of constraint functions of the design variables according to the heating system model and the design variables; An objective function is determined according to a plurality of constraint functions of the design variables.
[0012] In the above implementation process, based on the electrothermal coupling model, the objective function that changes with the resistance of the heating film is calculated. The objective function can require: the maximum temperature difference on the battery surface is minimized when heating stops, the battery consumes the least power per 1°C increase in temperature, the battery cutoff voltage is the highest during the heating process, and the average battery temperature rise rate is the largest, thereby ensuring the power of the entire vehicle, and achieving improved low-temperature cruising range and reduced low-temperature mileage attenuation.
[0013] Furthermore, the step of preprocessing the objective function to obtain the preprocessed objective function includes: Performing normalization processing on the multiple constraint functions of the design variables to obtain multiple normalized constraint functions; A normalized objective function is determined according to the normalized plurality of constraint functions.
[0014] In the above implementation process, due to the contradiction of the objective function, multiple constraint functions need to be normalized to normalize different orders of magnitude and units.
[0015] Furthermore, the step of obtaining the resistance target data of the heating film according to the heating target bias and the preprocessed target function includes: Determining a weighting coefficient according to the bias of the heating target; The resistance target data of the heating film is obtained according to the weighting coefficient and the normalized objective function.
[0016] In the above implementation process, the bias of the heating target is reflected by the weighting coefficient. Different weights can be given to the four reference indicators of heating time, temperature gradient, cut-off voltage and power consumption required for heating. Combined with the objective function, the minimum value of the objective function under different bias conditions is obtained (the resistance target data of the heating film is obtained), that is, the optimal resistance of the heating film.
[0017] In a second aspect, the present application provides a composite heating system for a power battery pack, comprising: a heating model unit, configured to establish a composite internal and external heating system model for a power battery pack, wherein the power battery pack includes a plurality of power batteries, each of which is provided with a heating film on its surface, and the heating film is connected in series with the power battery; an objective function unit, configured to obtain an objective function that follows the change of the resistance value of the heating film according to the heating system model; A preprocessing unit, configured to preprocess the objective function to obtain a preprocessed objective function; a resistance target unit, configured to obtain resistance target data of the heating film according to the heating target bias and the preprocessed target function; A control unit is used to control the composite heating of the power battery pack according to the resistance target data.
[0018] Furthermore, the heating model unit is also used for: Establishing an equivalent circuit model according to the voltage of the power battery, the battery state of charge, the average temperature of the battery surface and the resistance value of the heating film; Establishing a heat generation model based on battery mass, battery specific heat capacity, internal heat generation of the power battery, and external heat generation of the heating film; Establishing an electrothermal coupling model based on a heat conduction model between the heating film and the power battery; An internal and external composite heating system model of a power battery pack is established based on the equivalent circuit model, the heat generation model, and the electrothermal coupling model.
[0019] Furthermore, the heating model unit is also used for: Dividing the power battery into multiple equal parts along the length direction to obtain a battery multi-division model; Establishing an internal heat conduction model of the power battery according to the heat capacity, heat generation rate and thermal resistance of the power battery; A heat conduction model between the power batteries is established according to the heat source, heat capacity, thermal resistance of the heating film and the internal heat conduction model of the power battery.
[0020] Furthermore, the objective function unit is further configured to: determining design variables according to the resistance value of the heating film before heating; Obtaining a plurality of constraint functions of the design variables according to the heating system model and the design variables; An objective function is determined according to a plurality of constraint functions of the design variables.
[0021] Furthermore, the pre-processing unit is further configured to: Performing normalization processing on the multiple constraint functions of the design variables to obtain multiple normalized constraint functions; A normalized objective function is determined according to the normalized plurality of constraint functions.
[0022] Furthermore, the resistance target unit is further used for: Determining a weighting coefficient according to the bias of the heating target; The resistance target data of the heating film is obtained according to the weighting coefficient and the normalized objective function.
[0023] In a third aspect, the present application provides an electronic device comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method described in any one of the first aspects when executing the computer program.
[0024] In a fourth aspect, the present application provides a computer-readable storage medium having instructions stored thereon. When the instructions are executed on a computer, the computer executes the method as described in any one of the first aspects.
[0025] In a fifth aspect, the present application provides a computer program product, which, when running on a computer, enables the computer to execute the method as described in any one of the first aspects.
[0026] Other features and advantages disclosed in the present application will be described in the following description, or some features and advantages can be inferred or determined without doubt from the description, or can be learned by implementing the above-mentioned technology disclosed in the present application.
[0027] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.
[0029] Figure 1 A schematic flow chart of a composite heating method for a power battery pack provided in an embodiment of the present application; Figure 2 A schematic diagram of a process for establishing a heating system model provided in an embodiment of the present application; Figure 3A schematic diagram of a process for establishing an electrothermal coupling model provided in an embodiment of the present application; Figure 4 A schematic flow chart of another composite heating method for a power battery pack provided in an embodiment of the present application; Figure 5 A schematic diagram of a heating circuit for a power battery pack provided in an embodiment of the present application; Figure 6 A schematic diagram of an equivalent circuit model provided in an embodiment of the present application; Figure 7 A schematic diagram of an electrothermal coupling model provided in an embodiment of the present application; Figure 8 A structural block diagram of a composite heating system for a power battery pack provided in an embodiment of the present application; Figure 9 This is a structural block diagram of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION
[0030] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.
[0031] It should be noted that similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings. At the same time, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description and should not be understood as indicating or implying relative importance.
[0032] Generally, at low temperatures, the conduction rate of lithium ions slows down, significantly reducing the available power and energy of the power battery. Furthermore, a lithium plating layer forms on the anode surface, accelerating the degradation of the battery life and increasing the risk of battery life. This directly leads to poor power performance and a significant reduction in driving range for electric vehicles, seriously affecting their use in all climates. Currently, there are two main heating methods for lithium-ion power batteries: external heating and internal heating. External heating is less efficient and results in greater temperature inconsistency in the battery. Internal heating, on the other hand, has a more complex control mechanism for the preheating process, which can adversely affect the battery's cycle life and potentially lead to thermal runaway. Furthermore, the vehicle's power is poor, and its range is limited under low-temperature conditions.
[0033] In response to the technical problems raised above, the embodiments of the present application provide a composite heating method, system, electronic device and computer-readable storage medium for a power battery pack; the composite heating method for a power battery pack sets a heating film on the surface of the power battery, and the heating film and the power battery are connected in series; thereby, an internal and external composite heating system model of the power battery pack is established, and the resistance target data of the heating film is obtained based on the heating system model, and then the composite heating process of the power battery pack is controlled by the resistance target data; the composite heating method for a power battery pack performs composite heating on the power battery itself through the joint heat generation of the power battery and the metal film, which can achieve the technical effects of improving the power performance of the entire vehicle, improving the low-temperature cruising range and reducing the low-temperature mileage attenuation.
[0034] See Figure 1 , Figure 1 This is a flow chart of a composite heating method for a power battery pack provided in an embodiment of the present application. The composite heating method for a power battery pack includes the following steps: S100: Establishing a composite internal and external heating system model for a power battery pack, wherein the power battery pack includes a plurality of power batteries, each of which is provided with a heating film on its surface, and the heating film is connected in series with the power battery; S200: Obtaining an objective function that follows the change in resistance value of the heating film according to the heating system model; S300: Preprocessing the objective function to obtain a preprocessed objective function; S400: Obtaining resistance target data of the heating film according to the heating target bias and the pre-processed target function; S500: Controlling the composite heating of the power battery pack according to the resistance target data.
[0035] For example, the heating film provided in the embodiments of the present application can be a thin sheet of conductive film formed by attaching a conductive metal material to an insulating material, then covering the metal layer with a layer of insulating material. The conductive metal can be copper wire, which is shaped into a zigzag shape to increase the contact area between the metal film and the lithium-ion battery, ensuring more uniform heating. A power source is connected to both ends of the copper wire. When current flows through the copper wire, the resistance of the copper wire generates heat, which is transferred to the lithium-ion battery, thereby increasing the battery temperature.
[0036] Illustratively, the heating film and the power battery provided in the embodiment of the present application are connected in series with each other; thus, when the power battery is working, the internal heat generation of the power battery and the external heat generation of the heating film are combined, and the power battery and the heating film jointly generate heat, thereby achieving composite heating of the power battery itself.
[0037] For example, by establishing an internal-external composite (internal-external composite) heating system model of a power battery, it can be used to accurately describe the heating process of the power battery-heating film, thereby realizing control of the composite heating process of the power battery.
[0038] Exemplarily, the resistance target data can be the resistance target that the heating film needs to reach after the power battery is working and the heating film is energized. The resistance target can be regarded as the resistance of the optimal heating film; the resistance target data comprehensively considers the low-temperature battery power attenuation and the battery heating energy consumption. This composite heating method consumes less power, can restore the battery's available energy, and effectively improve the low-temperature cruising range.
[0039] The composite heating method for a power battery pack provided in an embodiment of the present application sets a heating film on the surface of the power battery, and the heating film and the power battery are connected in series; thereby, a composite internal and external heating system model of the power battery pack is established, and the resistance target data of the heating film is obtained according to the heating system model, and then the composite heating process of the power battery pack is controlled by the resistance target data; the composite heating method for the power battery pack performs composite heating on the power battery itself through the joint heat generation of the power battery and the metal film, and combines the advantages of internal heating so that the battery in an extremely low temperature environment can recover to the normal temperature discharge capacity in a relatively short time, effectively solving the weak pain points of low-temperature automobile power and improving the power of the entire vehicle; in addition, the composite heating method comprehensively considers the low-temperature battery power attenuation and the battery heating energy consumption, consumes less power, can restore the available energy of the battery, and effectively improves the low-temperature cruising range; therefore, the composite heating method for the power battery pack can achieve the technical effects of improving the power of the entire vehicle, improving the low-temperature cruising range, and reducing the attenuation of the low-temperature mileage.
[0040] See Figure 2 , Figure 2 A schematic diagram of the process of establishing a heating system model provided in an embodiment of the present application.
[0041] In some embodiments, S100: the step of establishing a combined internal and external heating system model of a power battery pack includes: S110: establishing an equivalent circuit model according to the voltage of the power battery, the battery state of charge, the average temperature of the battery surface, and the resistance value of the heating film; S120: Establishing a heat generation model based on the battery mass, battery specific heat capacity, internal heat generation of the power battery, and external heat generation of the heating film; S130: Establishing an electrothermal coupling model based on a heat conduction model between the heating film and the power battery; S140: Establishing an internal and external composite heating system model of the power battery pack based on the equivalent circuit model, the heat generation model, and the electrothermal coupling model.
[0042] For example, the equivalent circuit model can be used to describe the changes in the electrical characteristic parameters of the power battery during low-temperature heating, while the heat generation model can be used to characterize the energy transfer process between the power battery and the heating film during the heating process. Combined with the electrothermal coupling model, a composite internal and external heating system model of the power battery pack is established, which can be used to accurately describe the heating process of the power battery-heating film, thereby realizing the control of the composite heating process of the power battery.
[0043] See Figure 3 , Figure 3 A schematic diagram of the process of establishing an electrothermal coupling model provided in an embodiment of the present application.
[0044] In some embodiments, before the step of S130: establishing an electrothermal coupling model according to a heat conduction model between the heating film and the power battery, the method further includes: S131: Divide the power battery into multiple equal parts along the length direction to obtain a battery multi-division model; S132: Establishing an internal heat conduction model of the power battery based on the heat capacity, heat generation rate, and thermal resistance of the power battery; S133: Establishing a heat conduction model between the power batteries based on the heat source, heat capacity, thermal resistance of the heating film and the internal heat conduction model of the power batteries.
[0045] For example, considering the large inconsistency of the internal temperature changes of the power battery, the power battery is divided into multiple equal parts along the length direction to accurately calculate the temperature of each part of the power battery; then, combined with the heat source, heat capacity, and thermal resistance of the heating film, the heat conduction of the heating film to the battery can be accurately calculated, and a heat conduction model between the power batteries can be established.
[0046] See Figure 4 , Figure 4 A schematic flow chart of another composite heating method for a power battery pack provided in an embodiment of the present application.
[0047] In some embodiments, S200: the step of obtaining an objective function that follows the change in the resistance value of the heating film according to the heating system model includes: S210: Determining design variables according to the resistance value of the heating film before heating; S220: Obtaining multiple constraint functions of the design variables according to the heating system model and the design variables; S230: Determine an objective function according to a plurality of constraint functions of the design variables.
[0048] For example, based on the electrothermal coupling model, an objective function that changes with the resistance of the heating film is calculated. The objective function may require: the maximum temperature difference on the battery surface is minimized when heating stops, the battery consumes the least power per 1°C increase, the battery cutoff voltage is the highest during the heating process, and the average battery temperature rise rate is the largest, thereby ensuring the power of the entire vehicle, improving the low-temperature cruising range, and reducing the low-temperature mileage attenuation.
[0049] In some embodiments, S300: preprocessing the objective function to obtain the preprocessed objective function includes: S310: performing normalization processing on the multiple constraint functions of the design variables to obtain multiple normalized constraint functions; S320: Determine a normalized objective function according to the normalized plurality of constraint functions.
[0050] For example, due to the contradictory nature of the objective function, multiple constraint functions need to be normalized to normalize different orders of magnitude and units.
[0051] In some embodiments, S400: the step of obtaining the resistance target data of the heating film according to the heating target bias and the preprocessed target function includes: S410: Determine a weighting coefficient according to the heating target bias; S420: Obtaining resistance target data of the heating film according to the weighted coefficient and the normalized objective function.
[0052] For example, the bias of the heating target is reflected by the weighting coefficient. Different weights can be given to the four reference indicators of heating time, temperature gradient, cut-off voltage and power consumption required for heating. Combined with the objective function, the minimum value of the objective function under different bias conditions can be obtained (the resistance target data of the heating film is obtained), that is, the optimal resistance of the heating film.
[0053] In some implementation scenarios, combined with Figures 1 to 4 The specific implementation steps of the composite heating method of the power battery pack shown are as follows: Heating circuit such as Figure 5 As shown, Figure 5 Schematic diagram of the heating circuit of the power battery pack provided in an embodiment of the present application; the power battery discharges the heating film, generating Joule heat of the battery's internal resistance and Joule heat of the heating film's resistance, causing the battery to heat up rapidly; wherein the voltage acquisition module and the Hall sensor are used to collect voltage and current signals, the A / D converter converts the collected temperature signal into analog-to-digital, and the controller receives the voltage, current and temperature signals and transmits the control signal to the relay.
[0054] Step 1: Establish a power battery internal and external composite heating system model, which includes an equivalent circuit model, an electrothermal coupling model, etc. (1) Equivalent circuit model; The equivalent circuit model is used to describe the changes in the electrical characteristic parameters of the power battery during low-temperature heating, simplifying the battery into a first-order RC equivalent circuit model. The equivalent circuit model diagram is as follows Figure 6 As shown, the voltage U It consists of three parts: ; in: Part 1 U OCV is the open circuit voltage, and the second part is the parallel polarization internal resistance R p With polarized capacitance C p Voltage drop on U RC , the third part is the ohmic internal resistance R ohm The voltage drop across I is the working current during the heating process, R o is the heating film resistor; ; ; ; Where: SOC is the battery charge state, T is the average surface temperature of the battery; The heating film is a conductive metal and can be used as a balancing resistor in the heating circuit. Since the resistance of the metal changes with temperature, the relationship between the resistance of the heating film and temperature is as follows: ; in: R o Indicates the resistance of a single heating film. R o ' represents the initial value of the heating film resistance before heating, dR Indicates the change in heating film resistance with temperature.
[0055] (2) Heat production model; The energy transfer process during the heating process is that the battery self-discharges, transfers the electrical energy to the inside of the battery, and the battery generates heat. Q t Reversible thermal Q r and irreversible heat Q J , Q Jis the heat generation power, expressed as the Joule heat generated by the battery's ohmic internal resistance, Q r It is reversible entropy heat. Q t The heat is directly transferred to the inside of the battery, which is called internal heating of the battery. The battery discharges to the external heating film, and the electrical energy is transferred to the external heating film. The external resistance of the heating film R film Produces Joule heat Q film ; ; ; ; As mentioned above, the battery and the heating film form a closed-loop system for energy transfer. The heating system preheats the battery by generating heat inside the battery and transferring heat from the heating film to the battery. Q as follows: (3.4); According to the heat balance equation, we can get: (3.5); In the formula m For battery quality, c is the specific heat capacity of the battery; (3) Electrothermal coupling model; Considering the large inconsistency of the temperature change inside the battery, the battery is divided into three equal parts along the length direction (expressed as k 1, k 2, k 3) in order to accurately calculate the temperature of each part of the battery; The heat conduction model of each battery section is as follows Figure 4 , are determined by the heat capacity ( C batk ), heat production rate ( P b ) and thermal resistance( R dk ), of which C batk Describe the heat accumulation in each part of the battery, P bk is the internal resistance heat generation rate of each part of the battery, R dk represents the heat spread between adjacent parts of the battery, R a Represents the heat exchange between the battery and the surrounding environment, T batk ( k=1, 2, 3) represents the temperature of each part inside the battery, where T bat1 , T bat2 , T bat3 Batteries k 1, k 2, k 3. Average surface temperature, T a Is the ambient temperature, and the internal heat conduction model of the battery is established as:
[0056] in: η 1. η 2. η 3 are the heat distribution ratios of the battery internal resistance Joule heat near the tab, in the middle, and away from the tab, respectively. η 1+ η 2+ η 3=1; The heat conduction model between the heating film and the battery is composed of the heat source ( Q film ), heat capacity( C film ) and thermal resistance ( R film ) composition, calculate the heat conduction of the heating film to the battery as follows: ; in: P film is the heating rate of the heating film, R film Represents the heat transfer between the heating film and the battery, T film Indicates the average surface temperature of the heating film, T mean is the average temperature of the largest surface of the battery ( T mean1 and T mean2 represent the average temperature on both sides of the battery), T a Is the ambient temperature. R ohm , polarization resistance R p , polarized capacitance C p , heat capacity C film and thermal resistance R filmParameters such as can be obtained by parameter identification; in, Figure 7 A schematic diagram of an electrothermal coupling model provided in an embodiment of the present application; Step 2: Optimization of composite heating system parameters; Optimize the parameters of the composite heating system, namely the resistance value of the heating film: (1) Determine the design variables as x ={ R} T , R is the resistance value of the heating film before heating; (2) Based on step 1, establish an electrothermal coupling model and calculate the resistance of the heating film R The objective function of the change. The constraint function of the objective function and the design variables is expressed as: ; Among them, the objective function f 1( x ) requires that the maximum temperature difference on the battery surface be the smallest when heating stops, T is the battery temperature, T amb is the ambient temperature, t end is the moment to stop heating, the objective function f 2( x ) requires that the battery consumes the least amount of power for every 1℃ rise, and the objective function f 3( x ) requires that the battery cut-off voltage is the highest during the heating process, U jiezhi is the cut-off voltage during battery heating, the objective function f 4( x ) requires the battery average temperature rise rate to be the largest; (3) Normalize the objective function; Due to the contradictions of the objective functions, the four objective functions need to be normalized. The different orders of magnitude and units are normalized. The normalization method is as follows: ; in f * are the normalized results of the four objective functions respectively; In order to weigh the four objective functions, a single objective function with weighting coefficients can be expressed as: ; Where λ1, λ2, λ3, and λ4 are in the range of [0, 1], and λ1+λ2+λ3+λ4=1; (4) Obtain the optimal heating film resistance based on the heating target bias; The bias of the heating target is reflected by the weighted coefficients (λ1, λ2, λ3, λ4), and different weights can be given to the four reference indicators of heating time, temperature gradient, cut-off voltage and power consumption required for heating. Combined with the objective function formula f , the minimum value of the objective function under different bias conditions, that is, the optimal heating film resistance, is obtained; the bias of the heating target is reflected by the weighting coefficients (λ1, λ2, λ3, λ4). For example: if the weight of λ1 is large, the temperature difference at different positions of the battery is small, but the heating time is too long; if the weight of λ2 is large, the power consumption required for heating is small; if the weight of λ3 is large, the voltage value of the battery is high, which causes less damage to the battery; if the weight of λ4 is large, the heating speed is faster. Different weights are given to the four reference indicators of heating time, temperature gradient, cut-off voltage and power consumption required for heating according to the heating demand. Combined with the objective function formula f , and obtain the minimum value of the objective function under different bias conditions, that is, the optimal heating film resistance.
[0057] See Figure 8 , Figure 8 This is a structural block diagram of a composite heating system for a power battery pack provided in an embodiment of the present application. The composite heating system for a power battery pack includes: The heating model unit 100 is used to establish a composite internal and external heating system model of a power battery pack, wherein the power battery pack includes a plurality of power batteries, each of which is provided with a heating film on its surface; An objective function unit 200 is used to obtain an objective function that follows the change of the resistance value of the heating film according to the heating system model; A preprocessing unit 300 is used to preprocess the objective function to obtain a preprocessed objective function; The resistance target unit 400 is used to obtain the resistance target data of the heating film according to the heating target bias and the pre-processed target function; The control unit 500 is used to control the combined heating of the power battery pack according to the resistance target data.
[0058] In some embodiments, the heating model unit 100 is further configured to: An equivalent circuit model is established based on the voltage of the power battery, the battery state of charge, the average temperature of the battery surface and the resistance value of the heating film; Establish a heat generation model based on battery mass, battery specific heat capacity, internal heat generation of the power battery and external heat generation of the heating membrane; An electrothermal coupling model is established based on the heat conduction model between the heating film and the power battery; An internal and external composite heating system model of the power battery pack is established based on the equivalent circuit model, heat generation model and electrothermal coupling model.
[0059] In some embodiments, the heating model unit 100 is further configured to: Divide the power battery into multiple equal parts along the length direction to obtain a battery multi-division model; Establish an internal heat conduction model of the power battery based on the heat capacity, heat generation rate and thermal resistance of the power battery; A heat conduction model between power batteries is established based on the heat source, heat capacity, thermal resistance of the heating film and the internal heat conduction model of the power battery.
[0060] In some embodiments, the objective function unit 200 is further configured to: Determine the design variables based on the resistance value of the heating film before heating; According to the heating system model and the design variables, a plurality of constraint functions of the design variables are obtained; The objective function is determined based on multiple constraint functions of the design variables.
[0061] In some embodiments, the pre-processing unit 300 is further configured to: Performing normalization processing on multiple constraint functions of design variables to obtain multiple normalized constraint functions; A normalized objective function is determined according to the normalized plurality of constraint functions.
[0062] In some embodiments, the resistance target unit 400 is further used to: Determining a weighting coefficient according to the bias of the heating target; The resistance target data of the heating film is obtained according to the weighted coefficient and the normalized objective function.
[0063] It should be noted that the composite heating system of the power battery pack provided in the embodiment of the present application is Figures 1 to 7 The method embodiments shown correspond to the above and will not be described again here to avoid repetition.
[0064] This application also provides an electronic device, see Figure 9 , Figure 9 This is a block diagram of the structure of an electronic device provided in an embodiment of the present application. The electronic device may include a processor 510, a communication interface 520, a memory 530, and at least one communication bus 540. The communication bus 540 is used to enable direct communication between these components. The communication interface 520 of the electronic device in this embodiment of the present application is used to communicate signaling or data with other node devices. The processor 510 may be an integrated circuit chip with signal processing capabilities.
[0065] The processor 510 can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component. It can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of this application. A general-purpose processor can be a microprocessor, or the processor 510 can also be any conventional processor.
[0066] The memory 530 may be, but is not limited to, a random access memory (RAM), a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), etc. The memory 530 stores computer-readable instructions. When the computer-readable instructions are executed by the processor 510, the electronic device can perform the above-mentioned Figures 1 to 7 The various steps involved in the method embodiment.
[0067] Optionally, the electronic device may further include a storage controller and an input / output unit.
[0068] The memory 530, storage controller, processor 510, peripheral interface, and input / output units are electrically connected to each other directly or indirectly to enable data transmission or interaction. For example, these components can be electrically connected to each other via one or more communication buses 540. The processor 510 is used to execute executable modules stored in the memory 530, such as software function modules or computer programs included in the electronic device.
[0069] The input and output unit is used to provide users with the ability to create tasks and to create optional time periods or preset execution times for the tasks to enable interaction between the user and the server. The input and output unit can be, but is not limited to, a mouse and a keyboard.
[0070] I understand. Figure 9 The structure shown is for illustration only. The electronic device may also include Figure 9 More or fewer components than shown, or with Figure 9 Different configurations shown. Figure 9 Each component shown in the figure can be implemented by hardware, software or a combination thereof.
[0071] An embodiment of the present application further provides a storage medium having instructions stored thereon. When the instructions are run on a computer, the computer program is executed by a processor to implement the method described in the method embodiment. To avoid repetition, details are not given here.
[0072] The present application also provides a computer program product, which, when running on a computer, enables the computer to execute the method described in the method embodiment.
[0073] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architectures, functions and operations of the devices, methods and computer program products according to the multiple embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of the code, and the module, program segment or a part of the code contains one or more executable instructions for implementing the specified logical functions. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or can be implemented using a combination of dedicated hardware and computer instructions.
[0074] In addition, the functional modules in each embodiment of the present application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.
[0075] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard drives, read-only memories (ROM), random access memories (RAM), magnetic disks or optical disks.
[0076] The foregoing is merely an embodiment of the present application and is not intended to limit the scope of protection of the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included within the scope of protection of the present application. It should be noted that similar reference numerals and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined or explained in subsequent figures.
[0077] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.
[0078] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.
Claims
1. A composite heating method for a power battery pack, characterized in that: include: Establishing a model of a combined internal and external heating system for a power battery pack, wherein the power battery pack includes a plurality of power batteries, each of which has a heating film disposed on its surface, and the heating film is connected in series with the power battery; Obtaining an objective function that follows the change in the resistance value of the heating film according to the heating system model; Preprocessing the objective function to obtain a preprocessed objective function; Obtaining resistance target data of the heating film according to the heating target bias and the preprocessed target function; The composite heating of the power battery pack is controlled according to the resistance target data.
2. The composite heating method for a power battery according to claim 1, characterized in that: The steps to establish a combined internal and external heating system model for a power battery pack include: Establishing an equivalent circuit model according to the voltage of the power battery, the battery state of charge, the average temperature of the battery surface and the resistance value of the heating film; Establishing a heat generation model based on battery mass, battery specific heat capacity, internal heat generation of the power battery, and external heat generation of the heating film; Establishing an electrothermal coupling model based on a heat conduction model between the heating film and the power battery; An internal and external composite heating system model of a power battery pack is established based on the equivalent circuit model, the heat generation model, and the electrothermal coupling model.
3. The composite heating method for a power battery according to claim 2, characterized in that: Before the step of establishing an electrothermal coupling model according to the heat conduction model between the heating film and the power battery, the method further includes: Dividing the power battery into multiple equal parts along the length direction to obtain a battery multi-division model; Establishing an internal heat conduction model of the power battery according to the heat capacity, heat generation rate and thermal resistance of the power battery; A heat conduction model between the power batteries is established according to the heat source, heat capacity, thermal resistance of the heating film and the internal heat conduction model of the power battery.
4. The composite heating method for a power battery according to claim 1, characterized in that: The step of obtaining an objective function that follows the change of the resistance value of the heating film according to the heating system model includes: determining design variables according to the resistance value of the heating film before heating; Obtaining a plurality of constraint functions of the design variables according to the heating system model and the design variables; An objective function is determined according to a plurality of constraint functions of the design variables.
5. The composite heating method for a power battery according to claim 4, characterized in that: The step of preprocessing the objective function to obtain the preprocessed objective function includes: Performing normalization processing on the multiple constraint functions of the design variables to obtain multiple normalized constraint functions; A normalized objective function is determined according to the normalized plurality of constraint functions.
6. The composite heating method for a power battery according to claim 5, characterized in that: The step of obtaining the resistance target data of the heating film according to the heating target bias and the preprocessed target function comprises: Determining a weighting coefficient according to the bias of the heating target; The resistance target data of the heating film is obtained according to the weighting coefficient and the normalized objective function.
7. A composite heating system for a power battery pack, characterized in that: include: a heating model unit, configured to establish a composite internal and external heating system model for a power battery pack, wherein the power battery pack includes a plurality of power batteries, each of which is provided with a heating film on its surface, and the heating film is connected in series with the power battery; an objective function unit, configured to obtain an objective function that follows the change of the resistance value of the heating film according to the heating system model; A preprocessing unit, configured to preprocess the objective function to obtain a preprocessed objective function; a resistance target unit, configured to obtain resistance target data of the heating film according to the heating target bias and the preprocessed target function; A control unit is used to control the composite heating of the power battery pack according to the resistance target data.
8. The composite heating system for a power battery pack according to claim 7, characterized in that: The heating model unit is also used for: Establishing an equivalent circuit model according to the voltage of the power battery, the battery state of charge, the average temperature of the battery surface and the resistance value of the heating film; Establishing a heat generation model based on battery mass, battery specific heat capacity, internal heat generation of the power battery, and external heat generation of the heating film; Establishing an electrothermal coupling model based on a heat conduction model between the heating film and the power battery; An internal and external composite heating system model of a power battery pack is established based on the equivalent circuit model, the heat generation model, and the electrothermal coupling model.
9. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the composite heating method for a power battery pack according to any one of claims 1 to 6 are implemented.
10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores instructions, and when the instructions are executed on a computer, the computer is caused to execute the composite heating method for a power battery pack according to any one of claims 1 to 6.