Battery pulse current heating method, system, device, and medium in low temperature environment

Abstract

The application discloses a battery pulse current heating method, system, device and medium in a low-temperature environment, the heating method comprising: under a set environment temperature, providing an initial pulse current to a second battery pack based on an initial pulse duty ratio by a first battery pack; calculating heat generated when the initial pulse current flows through internal resistances of the first battery pack and the second battery pack based on a preset second-order equivalent circuit model; inputting the calculated heat into a lumped parameter thermal model to establish a curve of battery temperature changing with time; taking a pulse current amplitude and a pulse duty ratio as optimization variables, taking minimization of time required for the first battery pack and the second battery pack to reach their optimal working temperatures as a target, and rolling optimization of the lumped parameter thermal model and the second-order equivalent circuit model to determine optimal target pulse current and target pulse duty ratio. The application aims to improve heating efficiency and performance reliability of the battery in the low-temperature environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of battery thermal management systems, specifically to a battery pulse current heating method, system, device and medium in low temperature environment. BACKGROUND

[0002] Lithium-ion batteries are widely used in electric vehicles, portable electronic devices, and energy storage systems due to their high energy density and long cycle life. However, in low temperature environments (e.g. below -20℃), the performance of lithium-ion batteries significantly decreases, showing reduced capacity, increased internal resistance, and slowed charging speed. These problems limit the application of lithium-ion batteries in cold climates or high latitude regions.

[0003] To solve these problems, existing technologies have proposed various thermal management strategies, including external heating systems (such as electric heaters), internal heating methods (such as continuous current self-heating), and phase change material (PCM) cooling / heating systems. However, these methods have the following limitations: (1) External heating system: requires additional heating elements, increasing system complexity and energy consumption, and has low heating efficiency. (2) Internal self-heating: generates heat through continuous discharge / charge of the battery itself, but may cause battery overheating or shorten battery life. (3) Phase change material: although it can provide uniform temperature control, it has slow response speed and cannot quickly respond to low temperature start-up requirements.

[0004] Therefore, how to improve the heating efficiency of the battery in low temperature environment and ensure the reliability of the battery performance is a problem to be solved. SUMMARY

[0005] The present application provides a battery pulse current heating method, system, device and medium in low temperature environment, aiming to improve the heating efficiency of the battery in low temperature environment and ensure the reliability of the battery performance.

[0006] In one aspect, embodiments of the present application provide a battery pulse current heating method in a low temperature environment, the battery comprising a first battery pack and a second battery pack, the low temperature performance of the first battery pack being higher than that of the second battery pack, the heating method comprising: providing an initial pulse current to the second battery pack based on an initial pulse duty cycle through the first battery pack to heat the second battery pack at a set environment temperature; determining the internal resistance of the first battery pack and the second battery pack at the current state respectively based on a preset second-order equivalent circuit model, and calculating the heat generated when the initial pulse current flows through the internal resistance of the first battery pack and the second battery pack respectively according to Joule's law, the second-order equivalent circuit model being used to simulate the electrical behavior of the first battery pack and the second battery pack; inputting the calculated heat into a preset lumped parameter thermal model to establish a curve of the temperature of the battery changing with time, the lumped parameter thermal model being used to simulate the thermal behavior of the first battery pack and the second battery pack; performing rolling optimization on the lumped parameter thermal model and the second-order equivalent circuit model with pulse current amplitude and pulse duty cycle as optimization variables, and with the time required for the first battery pack and the second battery pack to reach their optimal working temperatures being minimized as the target, to determine the optimal target pulse current and target pulse duty cycle, so as to heat the battery in a low temperature environment based on the target pulse current and the target pulse duty cycle.

[0007] Optionally, in some embodiments of the present application, the expression of the lumped parameter thermal model is:

[0008] ,

[0009] wherein, is the battery mass of the battery, is the specific heat capacity, is the temperature rise rate, is the pulse duty cycle, is the pulse current amplitude, is the internal resistance of the battery, is the temperature of the battery, is the convective heat transfer coefficient, is the surface area of the battery, is the environment temperature.

[0010] Optionally, in some embodiments of the present application, the heating method further comprises: establishing the second-order equivalent circuit model, and the step of establishing the second-order equivalent circuit model specifically comprises: applying a preset pulse current excitation to the battery through a hybrid pulse power characteristic test, and synchronously collecting voltage response data and current data at a preset temperature; obtaining open circuit voltage measurement values of the battery at different states of charge based on the voltage response data and the current data, and establishing a mapping function relationship between the state of charge and the open circuit voltage measurement values using a polynomial fitting method; identifying a parameter group of the second-order equivalent circuit model by taking the current data as input and the voltage response data as expected output; configuring the identified parameter group in the second-order equivalent circuit model, and performing simulation based on the preset pulse current to obtain end voltage simulation data and state of charge simulation data of the battery; calculating open circuit voltage simulation values of the battery according to the state of charge simulation data and the mapping function relationship, and establishing a simulation relationship curve between the open circuit voltage simulation values and corresponding state of charge simulation values in the state of charge simulation data; comparing the simulation relationship curve with the mapping function relationship to determine whether the consistency reaches a preset accuracy standard, so as to verify the accuracy of the second-order equivalent circuit model.

[0011] Optionally, in some embodiments of the present application, the step of rolling optimization of the lumped parameter thermal model and the second-order equivalent circuit model to determine the optimal target pulse current and target pulse duty cycle specifically comprises: setting a pulse parameter set, the pulse parameter set including a plurality of pulse current amplitudes and a plurality of pulse duty cycles; inputting any pulse current amplitude and any pulse duty cycle in the pulse parameter set into an electro-thermal coupling model composed of the lumped parameter thermal model and the second-order equivalent circuit model to simulate to obtain a predicted temperature rise curve of the first battery pack and the second battery pack, and calculate the time required for the first battery pack and the second battery pack to reach their optimal working temperatures and the total energy consumption of the battery in a heating period according to the predicted temperature rise curve; calculating a fitness function value according to the time required for the first battery pack and the second battery pack to reach their optimal working temperatures and the total energy consumption; constantly generating a new combination of the pulse current amplitude and the pulse duty cycle by an optimization algorithm according to the fitness function value and whether the safety constraints of battery voltage and state of charge are met, until the improvement amount of the fitness function value is less than a preset threshold or the maximum number of iterations is reached, and determining the final pulse current amplitude and pulse duty cycle as the target pulse current and target pulse duty cycle.

[0012] Optionally, in some embodiments of the present application, the time required for the first battery pack and the second battery pack to reach their optimal working temperatures is expressed as:

[0013] ,

[0014] wherein, is the time required for both the first battery pack and the second battery pack to reach their optimal working temperatures, is the pulse current amplitude, is the pulse duty cycle, is the time for the first battery pack to reach the optimal working temperature, is the time for the second battery pack to reach the optimal working temperature;

[0015] the total energy consumption is expressed as:

[0016] ,

[0017] ,

[0018] wherein, is the power of the pulse current provided by the first battery pack, is the instantaneous voltage of the first battery pack, is the pulse current amplitude, is the time step, is the pulse state within a certain time step;

[0019] the fitness function value is expressed as:

[0020] ,

[0021] wherein, is the pulse current amplitude, is the pulse duty cycle, is the time required for both the first battery pack and the second battery pack to reach their optimal working temperatures, is the total energy consumption, are the weights of the equilibrium and respectively.

[0022] Optionally, in some embodiments of the present application, the heating method further comprises: based on the second-order equivalent circuit model, monitoring the terminal voltage and / or state of charge of the first battery pack and the second battery pack in real time; if the terminal voltage of any one of the first battery pack and the second battery pack exceeds the safe working window or the state of charge is lower than the preset threshold, interrupting the provision of the initial pulse current.

[0023] Optionally, in some embodiments of the present application, the optimal working temperature of the first battery pack and the optimal working temperature of the second battery pack are both in the range of 15℃ to 35℃.

[0024] In another aspect, the present application provides a battery pulse current heating system in a low temperature environment, comprising: a first battery pack, a second battery pack, a battery management module and a control circuit; the low temperature performance of the first battery pack is higher than that of the second battery pack; the battery management module is configured to establish a lumped parameter thermal model for simulating the thermal behavior of the first battery pack and the second battery pack and establish a second-order equivalent circuit model for simulating the electrical behavior of the first battery pack and the second battery pack; the control circuit is electrically connected with the first battery pack and the second battery pack respectively, for controlling the first battery pack to provide pulse current to the second battery pack with a specific pulse duty ratio based on the instruction issued by the battery management module; the battery management module is further configured to control the control circuit to heat based on an initial pulse duty ratio and an initial pulse current at a set environment temperature, determine the internal resistance of the first battery pack and the second battery pack in the current state respectively based on the second-order equivalent circuit model, and calculate the heat generated when the pulse current flows through the internal resistance of the first battery pack and the second battery pack respectively according to the Joule law, input the calculated heat into the lumped parameter thermal model to predict the temperature curve of the battery changing with time, and perform rolling optimization on the lumped parameter thermal model and the second-order equivalent circuit model with pulse current amplitude and pulse duty ratio as optimization variables, and with the time required for the first battery pack and the second battery pack to reach their optimal working temperatures as the target, to determine the optimal target pulse current and target pulse duty ratio, so as to heat the battery based on the target pulse current and the target pulse duty ratio in a low temperature environment.

[0025] In another aspect, the present application provides an electronic device, comprising a memory, a processor and a computer program stored on the memory and running on the processor, wherein the processor implements the battery pulse current heating method in a low temperature environment as described above when executing the computer program.

[0026] In another aspect, the present application provides a non-transitory computer readable storage medium having a computer program stored thereon, wherein the computer program is executed by a processor to implement the battery pulse current heating method in a low temperature environment as described above.

[0027] The application provides a battery pulse current heating method, system, device and medium in a low-temperature environment. A first battery group with excellent low-temperature performance is used to provide a pulse current to a second battery group with poor low-temperature performance, so as to simultaneously realize rapid self-heating of the first battery group and the second battery group. At the same time, by optimizing the amplitude and pulse duty cycle of the pulse current, it is ensured that the first battery group and the second battery group can reach their respective optimal working temperatures in the shortest time, thereby improving the heating efficiency of the battery in the low-temperature environment and ensuring the reliability of the battery performance on the basis of reducing the demand for external heating equipment. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a flowchart of the battery pulse current heating method in a low-temperature environment provided by the application;

[0029] Figure 2 is a circuit diagram of a second-order equivalent circuit model provided by the application;

[0030] Figure 3 is a SOC-OCV relationship diagram obtained by experiment in the battery pulse current heating method in a low-temperature environment provided by the application;

[0031] Figure 4 is a simulation diagram of the open-circuit voltage (OCV) of a battery changing with time in the battery pulse current heating method in a low-temperature environment provided by the application;

[0032] Figure 5 is a schematic diagram of the battery pulse current heating system in a low-temperature environment provided by the application. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the application will be described below with reference to the drawings in the embodiments of the application. The described technical solutions are only used to explain and describe the idea of the application, and should not be regarded as a limitation on the protection scope of the application.

[0034] As shown in Figure 1 The embodiments of the application provide a battery pulse current heating method in a low-temperature environment. The battery includes a first battery group and a second battery group, and the low-temperature performance of the first battery group is higher than that of the second battery group. Preferably, the first battery group is a sodium ion battery with a capacity retention rate ≥80% at-30℃, and the second battery group is a lithium ion battery with a capacity retention rate ≤80% at-30℃. Preferably, the first battery group is a sodium ion battery, which has the characteristics of maintaining a high capacity and fast charging capability at low temperature. The second battery group is a lithium ion battery, which usually has a significant performance decline below-20℃.

[0035] Specifically, the battery pulse current heating method in a low-temperature environment includes:

[0036] S10, providing an initial pulse current to the second battery pack based on an initial pulse duty ratio of the first battery pack at a set ambient temperature to heat the second battery pack.

[0037] Specifically, the first battery pack and the second battery pack are connected through a control circuit, which includes a switching element for generating and controlling the pulse current from the first battery pack to the second battery pack. The circuit design allows the first battery pack to act as the main power source at low temperature environment, providing pulse current to the second battery pack while generating heat through its internal resistance.

[0038] The low-temperature battery pulse current heating method provided in the application uses a first battery pack (such as a sodium ion battery) with excellent low-temperature performance as a pulse source to directly heat the internal resistance of a second battery pack (such as a lithium ion battery), with a short energy utilization path and high efficiency. By optimizing the algorithm to precisely control the pulse parameters, a very high heating efficiency is achieved. This greatly improves the range and starting speed of electric vehicles in low-temperature environments.

[0039] S20, based on a preset second-order equivalent circuit model, determining the internal resistance of the first battery pack and the second battery pack at the current state, respectively, and calculating the heat generated when the initial pulse current flows through the internal resistance of the first battery pack and the second battery pack according to Joule's law, the second-order equivalent circuit model is used to simulate the electrical behavior of the first battery pack and the second battery pack.

[0040] Specifically, the heating process is based on Joule heating principle. When the first battery pack provides pulse current to the second battery pack, heat is generated when the current flows through the internal resistance of the first battery pack and the second battery pack, resulting in temperature rise. The intermittent nature of the pulse current (compared to continuous current) can reduce the risk of battery overheating, improve heating uniformity and reduce the impact on battery life.

[0041] Specifically, a second-order equivalent circuit model is established to simulate the electrical behavior of the first battery pack and the second battery pack.

[0042] As shown in Figure 2 The second-order equivalent circuit model includes an open circuit voltage source (OCV), a series resistance (R0, representing ohmic resistance), and two RC parallel branches (R1C1 and R2C2, representing electrochemical polarization and concentration polarization).

[0043] In the embodiments of the application, the heating method further comprises establishing a second-order equivalent circuit model.

[0044] The step of establishing a second-order equivalent circuit model specifically comprises:

[0045] S201, apply a preset pulse current excitation to the battery through a mixed pulse power characteristic test, and synchronously collect voltage response data and current data at a preset temperature.

[0046] S202, based on the voltage response data and the current data, obtain open-circuit voltage measurement values of the battery at different states of charge, and establish a mapping function relationship between the state of charge and the open-circuit voltage measurement values by using a polynomial fitting method. Figure 3 to obtain a relationship curve between the state of charge and the open-circuit voltage measurement values of the battery.

[0047] S203, identify a parameter set of a second-order equivalent circuit model with the current data as input and the voltage response data as expected output.

[0048] S204, configure the identified parameter set in the second-order equivalent circuit model, and perform simulation based on the preset pulse current to obtain end voltage simulation data and state of charge simulation data of the battery.

[0049] S205, calculate an open-circuit voltage simulation value of the battery according to the state of charge simulation data and the mapping function relationship, and establish a simulation relationship curve between the open-circuit voltage simulation value and the corresponding state of charge simulation value in the state of charge simulation data.

[0050] Figure 4 The simulation effect of the change of the open-circuit voltage of the battery with time is shown.

[0051] S206, compare the simulation relationship curve with the mapping function relationship to determine whether the consistency of the two reaches a preset accuracy standard, so as to verify the accuracy of the second-order equivalent circuit model.

[0052] In the embodiments of the present application, the heating method further includes the following steps:

[0053] Based on the second-order equivalent circuit model, the end voltage and / or the state of charge of the first battery pack and the second battery pack are monitored in real time.

[0054] If the end voltage of any one of the first battery pack and the second battery pack exceeds a safe working window or the state of charge is lower than a preset threshold, the provision of the initial pulse current is interrupted.

[0055] Conventional self-heating or external heating can cause a large temperature difference (usually >8℃) inside and between the batteries, accelerating battery aging and bringing the risk of thermal runaway. The battery pulse current heating method in a low temperature environment provided in the application ensures temperature uniformity during heating by optimizing the intermittent characteristics (pulse duty ratio) of the pulse current and the dual-core synergistic heat generation mechanism. The measured data shows that the maximum temperature difference between the dual-core batteries can be controlled within 3℃, and the temperature difference inside the battery monomer is less than 5℃. Excellent temperature uniformity effectively avoids local overheating and lithium precipitation, greatly prolongs the cycle life of the battery system, and fundamentally improves the safety of the low-temperature heating process.

[0056] S30, input the calculated heat into a preset lumped parameter thermal model to establish a curve of temperature change of the battery over time, the lumped parameter thermal model being used to simulate thermal behaviors of the first battery pack and the second battery pack.

[0057] Specifically, a lumped parameter thermal model is established to simulate thermal behaviors of the first battery pack and the second battery pack.

[0058] In the embodiments of the application, the lumped parameter thermal model regards the battery as a thermal mass, and mainly considers the following factors: heat generated by Joule heating, heat transfer between the battery and the environment (through convective heat exchange), and the heat capacity and thermal conductivity of the battery.

[0059] In the embodiments of the application, the expression of the lumped parameter thermal model is:

[0060] ,

[0061] wherein, is a battery mass of the battery, is a specific heat capacity, is a temperature rise rate, is a pulse duty ratio, is a pulse current amplitude, is an internal resistance of the battery, is a temperature of the battery, is a convective heat exchange coefficient, is a surface area of the battery, is an ambient temperature.

[0062] S40, taking the pulse current amplitude and the pulse duty ratio as optimization variables, and taking the time required for the first battery pack and the second battery pack to reach their optimal working temperatures as the target, the lumped parameter thermal model and the second-order equivalent circuit model are rolling optimized to minimize the target, and the optimal target pulse current and the optimal target pulse duty ratio are determined to heat the battery based on the target pulse current and the target pulse duty ratio in a low temperature environment.

[0063] In the embodiments of the present application, an optimization algorithm such as particle swarm optimization (PSO) or genetic algorithm (GA) is used to search for the optimal pulse parameters (pulse current amplitude I and pulse duty cycle D).

[0064] In the embodiments of the present application, the steps of rolling optimization of the lumped parameter thermal model and the second-order equivalent circuit model to determine the optimal target pulse current and target pulse duty cycle include:

[0065] S401, set a pulse parameter set, the pulse parameter set including a plurality of pulse current amplitudes and a plurality of pulse duty cycles.

[0066] S402, input any pulse current amplitude and any pulse duty cycle in the pulse parameter set into the electro-thermal coupling model composed of the lumped parameter thermal model and the second-order equivalent circuit model, simulate to obtain the predicted temperature rise curves of the first battery pack and the second battery pack, and calculate the time required for the first battery pack and the second battery pack to reach their optimal working temperatures according to the predicted temperature rise curves, and the total energy consumption of the battery during the heating period.

[0067] By optimizing the amplitude of the pulse current and the pulse duty cycle, and heating the battery based on the target pulse current and the target pulse duty cycle in a low temperature environment, the temperature of the first battery pack and the second battery pack can be raised to their respective optimal working ranges in the shortest time.

[0068] In the embodiments of the present application, the optimal working temperature of the first battery pack and the optimal working temperature of the second battery pack are both in the range of 15℃ to 35℃. Specifically, the optimal working temperature of the first battery pack and the optimal working temperature of the second battery pack include 15℃, 16℃, 17℃, 18℃, 19℃, 20℃, 21℃, 22℃, 23℃, 24℃, 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, 31℃, 32℃, 33℃, 34℃, 35℃. Preferably, the optimal working temperature of the second battery pack is 25℃.

[0069] In the embodiments of the present application, the amplitude of the pulse current is in the range of 0 to 5 times the rated capacity of the battery. Specifically, the amplitude of the pulse current includes 0 times the rated capacity of the battery, 1 times the rated capacity of the battery, 2 times the rated capacity of the battery, 3 times the rated capacity of the battery, 4 times the rated capacity of the battery, and 5 times the rated capacity of the battery. For example, for a battery with a capacity of 100 Ah, 1C corresponds to a pulse current of 100 A. Then, 5C corresponds to a pulse current of 500 A.

[0070] In embodiments of the present application, the state of charge of the first battery pack and the second battery pack are both in the range of 10% to 90% of their rated capacity. Specifically, the state of charge of the first battery pack and the second battery pack are both at 10% of their rated capacity, 20% of their rated capacity, 30% of their rated capacity, 40% of their rated capacity, 50% of their rated capacity, 60% of their rated capacity, 70% of their rated capacity, 80% of their rated capacity, or 90% of their rated capacity.

[0071] In embodiments of the present application, the time required for the first battery pack and the second battery pack to reach their optimal operating temperature is expressed as:

[0072] ,

[0073] is the time required for the first battery pack and the second battery pack to reach their optimal operating temperature, is the pulse current amplitude, is the pulse duty cycle, is the time for the first battery pack to reach the optimal operating temperature, is the time for the second battery pack to reach the optimal operating temperature.

[0074] In embodiments of the present application, the time required for the first battery pack and the second battery pack to reach their optimal operating temperature is minimized. The constraints of the objective function include the maximum allowed temperature, the maximum pulse current, and the battery state of charge.

[0075] The total energy consumption is expressed as:

[0076] ,

[0077] ,

[0078] is the power of the pulse current provided to the first battery pack, is the instantaneous voltage of the first battery pack, is the pulse current amplitude, is the time step, is the pulse state in a certain time step.

[0079] S403, according to the time required for the first battery pack and the second battery pack to reach their optimal operating temperature and the total energy consumption, calculate the fitness function value.

[0080] The expression of the fitness function value is:

[0081] ​​,

[0082] wherein, is the pulse current amplitude, is the pulse duty cycle, is the time required for both the first battery pack and the second battery pack to reach their optimal working temperatures, is the total energy consumption, are the weights of the balance and respectively.

[0083] S404, according to the fitness function value and whether the safety constraints of the battery voltage and the state of charge are met, a new combination of the pulse current amplitude and the pulse duty cycle is continuously generated by the optimization algorithm until the improvement amount of the fitness function value is less than a preset threshold or the maximum number of iterations is reached, and the finally obtained pulse current amplitude and pulse duty cycle are determined as the target pulse current and the target pulse duty cycle.

[0084] The battery pulse current heating method in a low temperature environment provided by the present application utilizes the first battery pack with excellent low temperature performance to provide pulse current to the second battery pack with poor low temperature performance, so as to simultaneously realize the rapid self-heating of the first battery pack and the second battery pack. At the same time, by optimizing the amplitude and pulse duty cycle of the pulse current, it is ensured that the first battery pack and the second battery pack can reach their respective optimal working temperatures in the shortest time, thereby improving the heating efficiency of the battery in a low temperature environment and ensuring the reliability of the battery performance on the basis of reducing the demand for external heating equipment.

[0085] As shown in Figure 5 , the present application provides a battery pulse current heating system in a low temperature environment, comprising: a first battery pack 10, a second battery pack 20, a battery management module 30 and a control circuit 40.

[0086] Specifically, the low temperature performance of the first battery pack 10 is higher than that of the second battery pack 20. Among them, the first battery pack 10 is a battery with a capacity retention rate ≥80% at-30℃, and the second battery pack 20 is a battery with a capacity retention rate ≤80% at-30℃. Preferably, the first battery pack 10 is a sodium ion battery, which has the characteristics of still maintaining high capacity and fast charging capability at low temperature. The second battery pack 20 is a lithium ion battery, which usually has a significant performance decline below-20℃.

[0087] Specifically, the battery management module 30 is configured to establish a lumped parameter thermal model for simulating the thermal behavior of the first battery pack 10 and the second battery pack 20, and to establish a second-order equivalent circuit model for simulating the electrical behavior of the first battery pack 10 and the second battery pack 20.

[0088] Specifically, the control circuit 40 is electrically connected with the first battery pack 10 and the second battery pack 20 respectively, and is configured to control the first battery pack 10 to provide the second battery pack 20 with the pulsed current at a specific pulse duty ratio based on the instruction issued by the battery management module 30.

[0089] Specifically, the battery management module 30 is further configured to control the control circuit 40 to heat the first battery pack 10 and the second battery pack 20 based on the initial pulse duty ratio and the initial pulse current at the set ambient temperature, determine the internal resistance of the first battery pack 10 and the second battery pack 20 at the current state based on the second-order equivalent circuit model, and calculate the heat generated by the pulsed current flowing through the internal resistance of the first battery pack 10 and the second battery pack 20 according to the Joule law, and input the calculated heat into the lumped parameter thermal model to predict the curve of the temperature change of the battery over time.

[0090] Specifically, the battery management module 30 is further configured to take the pulse current amplitude and the pulse duty ratio as the optimization variables, minimize the time required for the first battery pack 10 and the second battery pack 20 to reach their optimal working temperatures as the target, and perform rolling optimization on the lumped parameter thermal model and the second-order equivalent circuit model to determine the optimal target pulse current and the target pulse duty ratio, so as to heat the battery based on the target pulse current and the target pulse duty ratio in the low-temperature environment and control the control circuit 40 to execute.

[0091] Specifically, the heating system further comprises a temperature sensor 50 for monitoring the temperature of the first battery pack 10 and the second battery pack 20 in real time.

[0092] The low-temperature environment battery pulsed current heating system provided by the present application utilizes the first battery pack 10 with excellent low-temperature performance to provide the second battery pack 20 with pulsed current, so as to simultaneously realize the rapid self-heating of the first battery pack 10 and the second battery pack 20. At the same time, by optimizing the amplitude of the pulsed current and the pulse duty ratio, it is ensured that the first battery pack 10 and the second battery pack 20 can reach their respective optimal working temperatures in the shortest time, thereby improving the heating efficiency of the battery in the low-temperature environment and ensuring the reliability of the battery performance on the basis of reducing the demand for external heating equipment.

[0093] The low-temperature environment battery pulsed current heating system provided by the present application does not need to increase additional external heating elements (such as PTC heating film), and fully utilizes the existing dual-core battery architecture and the computing power of the BMS (battery management module 30) in the system for pulse control and optimization. This not only reduces the system complexity, weight and manufacturing cost, but also saves the valuable internal space of the battery pack. The whole scheme is a kind of efficient, low-cost and integrated thermal management solution.

[0094] The low-temperature environment battery pulse current heating system provided by the application realizes battery heating by using the low-temperature environment battery pulse current heating method provided by the application, and the specific steps are not described here.

[0095] In another aspect, the application provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, and the processor implements the low-temperature environment battery pulse current heating method as above when executing the computer program.

[0096] In another aspect, the application provides a non-transitory computer readable storage medium having a computer program stored thereon, and the computer program is executed by a processor to implement the low-temperature environment battery pulse current heating method as above.

[0097] The above describes a low-temperature environment battery pulse current heating method, system, device and medium of the embodiments of the application in detail, and the above embodiment description is only for the purpose of helping to understand the core idea of the application, and the above description should not be understood as limiting the protection scope of the application.

Claims

1. A method for heating a battery with pulsed current in a low-temperature environment, characterized in that, The battery includes a first battery pack and a second battery pack, wherein the low-temperature performance of the first battery pack is higher than that of the second battery pack, and the heating method includes: At a set ambient temperature, the first battery pack provides an initial pulse current to the second battery pack based on an initial pulse duty cycle to heat the second battery pack. Based on a preset second-order equivalent circuit model, the internal resistances of the first battery pack and the second battery pack in the current state are determined respectively, and the heat generated when the initial pulse current flows through the internal resistances of the first battery pack and the second battery pack is calculated according to Joule's law. The second-order equivalent circuit model is used to simulate the electrical behavior of the first battery pack and the second battery pack. The calculated heat is input into a preset lumped parameter thermal model to establish a curve of the battery temperature changing over time. The lumped parameter thermal model is used to simulate the thermal behavior of the first battery pack and the second battery pack. Using the pulse current amplitude and pulse duty cycle as optimization variables, and aiming to minimize the time required for both the first and second battery packs to reach their optimal operating temperatures, rolling optimization is performed on the lumped parameter thermal model and the second-order equivalent circuit model to determine the optimal target pulse current and target pulse duty cycle, so as to heat the battery in a low-temperature environment based on the target pulse current and target pulse duty cycle.

2. The battery pulse current heating method in a low-temperature environment according to claim 1, characterized in that, The expression for the lumped parameter thermal model is: ， in, The battery mass is the mass of the battery. For specific heat capacity, For the rate of temperature rise, The pulse duty cycle is... The amplitude of the pulse current. The internal resistance of the battery is... The temperature of the battery, The convective heat transfer coefficient is... The surface area of ​​the battery is... The ambient temperature is mentioned.

3. The battery pulse current heating method in a low-temperature environment according to claim 1, characterized in that, The heating method further includes: establishing the second-order equivalent circuit model. The steps for establishing the second-order equivalent circuit model specifically include: By performing a hybrid pulse power characteristic test, a preset pulse current excitation is applied to the battery, and voltage response data and current data at a preset temperature are collected simultaneously. Based on the voltage response data and the current data, the open-circuit voltage measurement values ​​of the battery under different states of charge are obtained, and a polynomial fitting method is used to establish a mapping function relationship between the state of charge and the open-circuit voltage measurement values. Using the current data as input and the voltage response data as the desired output, the parameter set of the second-order equivalent circuit model is identified. The identified parameter set is configured in the second-order equivalent circuit model, and simulation is performed based on the preset pulse current to obtain the battery terminal voltage simulation data and state of charge simulation data. Based on the relationship between the state of charge simulation data and the mapping function, the simulated open-circuit voltage of the battery is calculated, and a simulation relationship curve between the simulated open-circuit voltage and the corresponding simulated state of charge in the state of charge simulation data is established. The simulation relationship curve is compared with the mapping function relationship to determine whether the consistency between the two reaches the preset accuracy standard, so as to verify the accuracy of the second-order equivalent circuit model.

4. The battery pulse current heating method in a low-temperature environment according to claim 1, characterized in that, The step of performing rolling optimization on the lumped parameter thermal model and the second-order equivalent circuit model to determine the optimal target pulse current and target pulse duty cycle specifically includes: A pulse parameter set is defined, the pulse parameter set including multiple pulse current amplitudes and multiple pulse duty cycles; The amplitude of any pulse current and the duty cycle of any pulse in the pulse parameter set are input into the electro-thermal coupling model composed of the lumped parameter thermal model and the second-order equivalent circuit model. The predicted temperature rise curves of the first battery pack and the second battery pack are obtained by simulation. Based on the predicted temperature rise curves, the time required for the first battery pack and the second battery pack to reach their optimal operating temperature and the total energy consumption of the battery in the heating cycle are calculated. The fitness function value is calculated based on the time required for both the first and second battery packs to reach their optimal operating temperatures and the total energy consumption. Based on the fitness function value and whether the safety constraints of battery voltage and state of charge are met, a new combination of pulse current amplitude and pulse duty cycle is continuously generated through an optimization algorithm until the improvement of the fitness function value is less than a preset threshold or the maximum number of iterations is reached. The final pulse current amplitude and pulse duty cycle are then determined as the target pulse current and the target pulse duty cycle.

5. The battery pulse current heating method in a low-temperature environment according to claim 4, characterized in that, Time required for both the first and second battery packs to reach their optimal operating temperature The expression is: ， in, This is the time required for both the first battery pack and the second battery pack to reach their optimal operating temperature. The amplitude of the pulse current. The pulse duty cycle is... The time it takes for the first battery pack to reach its optimal operating temperature. The time it takes for the second battery pack to reach its optimal operating temperature; The total energy consumption The expression is: ， ， in, The power of the pulse current provided to the first battery pack. It is the instantaneous voltage of the first battery pack. The amplitude of the pulse current. For time step, The pulse state within a certain time step; The expression for the fitness function value is: ， in, The amplitude of the pulse current. The pulse duty cycle is... This is the time required for both the first battery pack and the second battery pack to reach their optimal operating temperature. The total energy consumption is mentioned above. They are in balance and The weight.

6. The battery pulse current heating method in a low-temperature environment according to claim 1 or 4, characterized in that, The heating method further includes: Based on the second-order equivalent circuit model, the terminal voltage and / or state of charge of the first battery pack and the second battery pack are monitored in real time. If the terminal voltage of either the first battery pack or the second battery pack exceeds the safe operating window or the state of charge is lower than a preset threshold, the provision of the initial pulse current is interrupted.

7. The battery pulse current heating method in a low-temperature environment according to claim 1, characterized in that, The optimal operating temperature range for both the first battery pack and the second battery pack is 15°C to 35°C.

8. A battery pulse current heating system for low-temperature environments, characterized in that, include: First battery pack, second battery pack, battery management module and control circuit; The first battery pack has better low-temperature performance than the second battery pack. The battery management module is configured to establish a lumped parameter thermal model to simulate the thermal behavior of the first battery pack and the second battery pack, and to establish a second-order equivalent circuit model to simulate the electrical behavior of the first battery pack and the second battery pack. The control circuit is electrically connected to the first battery pack and the second battery pack respectively, and is used to control the first battery pack to provide pulse current to the second battery pack with a specific pulse duty cycle based on the instructions issued by the battery management module. The battery management module is also configured to control the control circuit to heat the battery based on the initial pulse duty cycle and the initial pulse current at a set ambient temperature. Based on the second-order equivalent circuit model, the internal resistance of the first battery pack and the second battery pack in the current state is determined respectively. The heat generated when the pulse current flows through the internal resistance of the first battery pack and the second battery pack is calculated according to Joule's law. The calculated heat is input into the lumped parameter thermal model to predict the temperature change curve of the battery over time. Furthermore, using pulse current amplitude and pulse duty cycle as optimization variables, and aiming to minimize the time required for both the first and second battery packs to reach their optimal operating temperatures, rolling optimization is performed on the lumped parameter thermal model and the second-order equivalent circuit model to determine the optimal target pulse current and target pulse duty cycle, so as to heat the battery in a low-temperature environment based on the target pulse current and target pulse duty cycle.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the battery pulse current heating method in a low-temperature environment as described in any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the battery pulse current heating method in a low-temperature environment as described in any one of claims 1 to 7.

Images