Battery heating methods, devices, vehicles and storage media

Abstract

This application provides a battery heating method, apparatus, vehicle, and storage medium. The method includes: after the vehicle is successfully connected to a charging pile, obtaining the current cell temperature of the battery in the vehicle; if the current cell temperature is lower than a first temperature threshold, first intermittently discharging the battery in a first mode, and then intermittently discharging the battery in a second mode to raise the battery temperature. This application enables the battery to generate Joule heat and electrochemical polarization heat under pulsed current in low-temperature environments due to the inherent high polarization resistance and ohmic resistance of the battery, thereby achieving internal self-heating of the battery and raising the battery temperature.

Description

Technical Field

[0001] This application relates to the field of vehicle technology, and in particular to a battery heating method, device, vehicle, and storage medium. Background Technology

[0002] With the rapid development of the new energy vehicle industry, vehicles need to adapt to more complex climatic conditions, especially the challenges of adaptability in low-temperature environments.

[0003] However, in low-temperature environments, the charging and discharging capabilities of power batteries decrease due to the increased viscosity of the electrolyte and the reduced lithium-ion transport rate. Direct charging at these temperatures results in low charging efficiency and can easily lead to lithium plating on the negative electrode, causing battery damage. Therefore, in low-temperature environments, heating of the power battery is necessary to ensure both charging efficiency and safety.

[0004] In related technologies, PTC heaters are typically used to heat the battery. However, on the one hand, this external heating method has a long heat conduction path and low heating efficiency. On the other hand, it easily creates temperature gradients inside and outside the battery, leading to uneven heating of the cells and localized polarization, affecting battery consistency and lifespan. Summary of the Invention

[0005] This application provides a battery heating method, device, vehicle, and storage medium that can generate Joule heat and electrochemical polarization heat under pulsed current in low-temperature environments due to the inherent high polarization resistance and ohmic resistance of the battery, thereby achieving internal self-heating of the battery and raising its temperature.

[0006] In a first aspect, embodiments of this application provide a battery heating method, which includes: after a vehicle is successfully connected to a charging pile, obtaining the current cell temperature of the battery in the vehicle; if the current cell temperature is less than a first temperature threshold, first intermittently discharging the battery in a first mode, and then intermittently discharging the battery in a second mode, so as to raise the temperature of the battery.

[0007] In one possible implementation, in a first mode, the battery discharge rate varies with the cell temperature; in a second mode, the battery discharge rate is a first discharge rate; the first discharge rate is greater than or equal to the battery's maximum discharge rate in the first mode.

[0008] In one possible implementation, the above-mentioned method of intermittently discharging the battery in a first mode and then intermittently discharging the battery in a second mode includes: firstly, alternatingly discharging and charging the battery in the first mode, and then alternatingly discharging and charging the battery in the second mode.

[0009] In one possible implementation, in the first mode, the process of alternating discharge and charge of the battery includes multiple first charge-discharge cycles. In each first charge-discharge cycle, the battery is first discharged and then charged. The discharge rate of the battery in the first charge-discharge cycle is greater than the charging rate in the first charge-discharge cycle.

[0010] In the second mode, the process of alternating discharge and charge of the battery includes multiple second charge-discharge cycles. In each second charge-discharge cycle, the battery is first discharged and then charged. The discharge rate of the battery in the second charge-discharge cycle is equal to the charging rate in the second charge-discharge cycle, and the discharge duration of the battery in the second charge-discharge cycle is equal to the charging duration in the second charge-discharge cycle.

[0011] In one possible implementation, each first charge-discharge cycle includes a first discharge phase and a first charge phase. The above-mentioned alternating discharge and charge of the battery in the first mode includes: when performing the first discharge phase of the first charge-discharge cycle, if the current cell voltage of the battery meets a first preset condition, then switching to the first charge phase of the first charge-discharge cycle; when performing the first charge phase of the first charge-discharge cycle, if the current cell voltage of the battery meets a second preset condition, or if the duration of the first charge phase is greater than a first duration threshold, then switching to the first discharge phase of the next first charge-discharge cycle.

[0012] In one possible implementation, the first preset condition includes at least one of the following: the current cell voltage is less than a first voltage threshold; the duration for which the current cell voltage is less than the first voltage threshold is greater than or equal to a second duration threshold.

[0013] The second preset condition includes at least one of the following: the current cell voltage is greater than the second voltage threshold; the duration for which the current cell voltage is greater than the second voltage threshold is greater than or equal to the third duration threshold.

[0014] In one possible implementation, the process of alternately discharging and charging the battery in a first mode includes a first control phase and a second control phase performed sequentially; the aforementioned alternate discharging and charging of the battery in the first mode includes: executing the first control phase, wherein the discharge rate of the battery in the first control phase is a second discharge rate, and the charging rate of the battery in the first control phase is a first charging rate; if the current cell temperature rises to a second temperature threshold, the process switches from the first control phase to the second control phase, wherein the discharge rate of the battery in the second control phase is a third discharge rate, and the charging rate of the battery in the second control phase is a second charging rate, the third discharge rate is greater than the second discharge rate, and the second charging rate is greater than or equal to the first charging rate.

[0015] In one possible implementation, the above-mentioned alternating discharge and charge of the battery in a first mode and then alternating discharge and charge of the battery in a second mode includes: obtaining the current state of charge of the battery cells; if the current state of charge of the battery cells meets a third preset condition, then alternating discharge and charge of the battery in the first mode; after running the first mode, re-obtaining the current state of charge of the battery cells; if the re-obtained current state of charge of the battery cells meets a fourth preset condition, then alternating discharge and charge of the battery in the second mode.

[0016] In one possible implementation, the third preset condition includes at least one of the following: the current state of charge of the battery cell is greater than the first state of charge threshold; the duration for which the current state of charge of the battery cell is greater than the first state of charge threshold is greater than or equal to a fourth duration threshold.

[0017] The fourth preset condition includes at least one of the following: the current state of charge of the battery cell is less than or equal to the first state of charge threshold; the duration during which the current state of charge of the battery cell is less than or equal to the first state of charge threshold is greater than or equal to the fifth duration threshold.

[0018] In one possible implementation, in the first mode, the process of alternating discharge and charge of the battery includes multiple first charge-discharge cycles; after running the first mode, the method further includes: if the duration of the discharge phase in the first mode meets a fifth preset condition, then the battery is alternately discharged and charged in the second mode; wherein, the fifth preset condition is that in a consecutive preset number of first charge-discharge cycles, the duration of the discharge phase in each first charge-discharge cycle is greater than a sixth duration threshold; or, if the target cell voltage in the first mode is less than a third voltage threshold, then the battery is alternately discharged and charged in the second mode; wherein, the target cell voltage is the cell voltage at the end of the charging phase in any first charge-discharge cycle.

[0019] In one possible implementation, after obtaining the current state of charge of the battery cells, the method further includes: if the current state of charge of the battery cells does not meet a third preset condition, then the battery is alternately discharged and charged in a second mode.

[0020] Secondly, embodiments of this application provide a battery heating device, the device comprising:

[0021] The acquisition module is used to acquire the current cell temperature of the battery in the vehicle after the vehicle is successfully connected to the charging pile.

[0022] The control module is used to intermittently discharge the battery in a first mode and then intermittently discharge the battery in a second mode when the current cell temperature is lower than a first temperature threshold, so as to raise the battery temperature.

[0023] Thirdly, embodiments of this application provide a vehicle, including: a memory and a processor;

[0024] The memory stores the instructions that the computer executes;

[0025] The processor executes computer execution instructions stored in memory, causing the processor to perform the first aspect and / or various possible implementations of the first aspect as described above.

[0026] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the first aspect and / or various possible implementations of the first aspect.

[0027] Fifthly, embodiments of this application provide a computer program product, including a computer program that, when executed by a processor, implements the first aspect and / or various possible implementations of the first aspect.

[0028] In this embodiment, after the vehicle is successfully connected to the charging pile, when the current cell temperature of the battery in the vehicle is lower than a first temperature threshold, the battery is first intermittently discharged in a first mode, and then intermittently discharged in a second mode. In this way, under low-temperature conditions, intermittent discharge in the first mode causes the battery's inherent high polarization resistance and ohmic resistance to generate Joule heat and electrochemical polarization heat under pulsed current, achieving internal self-heating of the battery and increasing its temperature rise rate. Furthermore, intermittent discharge avoids the risk of lithium plating on the negative electrode caused by charging at low temperatures, improving battery safety under low-temperature conditions while ensuring a high temperature rise rate. In addition, intermittent discharge in the first mode also allows for the slow release of battery energy as the battery temperature rises.

[0029] Furthermore, after running the first mode, intermittently discharging the battery in the second mode can prevent the battery from becoming too low in power, avoid over-discharge, and extend the battery's lifespan. Attached Figure Description

[0030] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0031] Figure 1 A schematic diagram illustrating an application scenario of a battery heating method provided in this application embodiment;

[0032] Figure 2 A schematic flowchart illustrating a battery heating method provided in an embodiment of this application;

[0033] Figure 3 A schematic flowchart illustrating another battery heating method provided in an embodiment of this application;

[0034] Figure 4 A schematic flowchart illustrating another battery heating method provided in this application embodiment;

[0035] Figure 5 A schematic diagram of the current rate change curve for low-temperature heating provided in an embodiment of this application;

[0036] Figure 6 This is a schematic diagram of the structure of a battery heating device provided in an embodiment of this application;

[0037] Figure 7 This is a structural schematic diagram of a vehicle provided in an embodiment of this application. Detailed Implementation

[0038] The embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described below do not represent all embodiments consistent with this application. They are merely examples of systems and methods consistent with some aspects of this application as detailed in the claims.

[0039] It should be noted that the brief descriptions of terms in this application are only for the convenience of understanding the embodiments described below, and are not intended to limit the embodiments of this application. Unless otherwise stated, these terms should be understood in their ordinary and common meaning.

[0040] The terms "first," "second," "third," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar or related objects or entities, and do not necessarily imply a specific order or sequence, unless otherwise specified. It should be understood that such terms are interchangeable where appropriate.

[0041] The terms “comprising” and “having”, and any variations thereof, are intended to cover but not exclude inclusion, for example, a product or device that includes a range of components is not necessarily limited to all of the components that are clearly listed, but may include other components that are not clearly listed or that are inherent to such product or device.

[0042] The term "module" refers to any known or subsequently developed hardware, software, firmware, artificial intelligence, fuzzy logic, or combination of hardware and / or software code that is capable of performing the functions associated with that element.

[0043] With the rapid development of the new energy vehicle industry, vehicles need to adapt to more complex climatic conditions, especially the challenges of adaptability in low-temperature environments.

[0044] However, in low-temperature environments, the charging and discharging capabilities of power batteries decrease due to the increased viscosity of the electrolyte and the reduced lithium-ion transport rate. Direct charging at these temperatures results in low charging efficiency and can easily lead to lithium plating on the negative electrode, causing battery damage. Therefore, in low-temperature environments, heating of the power battery is necessary to ensure both charging efficiency and safety.

[0045] In related technologies, PTC heaters are typically used to heat the battery. However, on the one hand, this external heating method has a long heat conduction path and low heating efficiency. On the other hand, it easily creates temperature gradients inside and outside the battery, leading to uneven heating of the cells and localized polarization, affecting battery consistency and lifespan.

[0046] In view of this, this application provides a battery heating method. After the vehicle is successfully connected to the charging pile, the current cell temperature of the battery in the vehicle is obtained. If the current cell temperature is lower than a first temperature threshold, the battery is first intermittently discharged in a first mode, and then intermittently discharged in a second mode to raise the battery temperature. In the first mode, the battery discharge rate changes with the cell temperature. In the second mode, the battery discharge rate is a first discharge rate. The first discharge rate is greater than or equal to the maximum discharge rate of the battery in the first mode.

[0047] In this way, after the vehicle successfully connects to the charging station, when the current cell temperature of the battery in the vehicle is lower than a first temperature threshold, the battery is first intermittently discharged in the first mode, and then intermittently discharged in the second mode. In this low-temperature environment, the battery's inherent high polarization resistance and ohmic resistance generate Joule heat and electrochemical polarization heat under pulsed current, achieving internal self-heating of the battery and raising its temperature. Furthermore, by intermittently discharging the battery, the risk of lithium plating on the negative electrode caused by charging in low-temperature environments can be avoided, improving the safety of battery heating in low-temperature environments.

[0048] Furthermore, in the first mode, the battery discharge rate is adjusted according to the cell temperature change, ensuring both heating efficiency and safety during low-temperature battery heating, thus preventing damage to the battery. In the second mode, a larger initial discharge rate is used to control the battery for intermittent discharge, which further improves the battery heating rate and shortens the battery heating time.

[0049] Before introducing the battery heating method provided in the embodiments of this application, the application scenarios of the battery heating method will be explained first.

[0050] The battery heating method provided in this application can be applied to vehicle charging scenarios, specifically, scenarios where a larger current is used to charge the battery in a low-temperature environment. In a low-temperature environment, the vehicle establishes a connection with a charging station. When the vehicle's battery meets the low-temperature heating conditions (e.g., the current cell temperature is less than a first temperature threshold, hereinafter), it enters a low-temperature heating stage. During the low-temperature heating stage, the battery is intermittently discharged to raise its temperature. More specifically, during the low-temperature heating stage, the battery is first intermittently discharged in a first mode, and then intermittently discharged in a second mode. In the first mode, the battery's discharge rate changes with the battery temperature. In the second mode, the battery's discharge rate is a preset discharge rate, which is greater than or equal to the maximum discharge rate in the first mode.

[0051] During the heating process of the battery (i.e., the low-temperature heating stage), the battery temperature is acquired in real time. When the battery temperature meets the charging conditions, the heating of the battery is stopped and the charging stage begins.

[0052] Figure 1 This is a schematic diagram illustrating an application scenario of a battery heating method provided in an embodiment of this application.

[0053] like Figure 1 As shown, this scenario can include a vehicle (i.e., the vehicle-side), a charging pile, an energy storage cabinet, and the power grid. The charging pile connects to both the energy storage cabinet and the power grid, and after the vehicle successfully connects to the charging pile, it charges the vehicle's power battery (i.e., the battery) based on the capabilities of the energy storage cabinet and the power grid. Furthermore, in low-temperature environments, the vehicle's Battery Management System (BMS) can intermittently discharge the battery to raise its temperature. Specifically, during the low-temperature heating of the battery, the energy storage cabinet acts as a receiver of the battery's discharge current. That is, the current output by the battery during the intermittent discharge phase flows back to the energy storage cabinet via the charging pile, thus forming a complete power transmission loop and providing energy interaction support for the battery's high-rate pulse discharge.

[0054] In some embodiments, under low-temperature conditions, the vehicle's battery management system alternately discharges and charges the battery to raise its temperature. Specifically, during the low-temperature heating of the battery, in the discharge phase, the energy storage cabinet can act as a receiver of the battery's output current, meaning the battery's output current flows back to the energy storage cabinet via the charging pile; in the charging phase, the energy storage cabinet and / or the grid terminal reverse-charge the battery by outputting current through the charging pile. Through the bidirectional energy interaction between the energy storage cabinet and the battery, a complete power transmission loop is formed, providing energy interaction support for the battery's pulsed alternating charging and discharging.

[0055] The battery heating method provided in this application embodiment will be described in detail below with reference to the accompanying drawings and application scenarios.

[0056] Figure 2 This is a schematic flowchart illustrating a battery heating method provided in an embodiment of this application. Figure 2 As shown, the battery heating method may include the following steps:

[0057] S201: After the vehicle is successfully connected to the charging station, the current cell temperature of the battery in the vehicle is obtained.

[0058] Specifically, after detecting that the vehicle has successfully connected to the charging station, the vehicle's battery management system obtains the current cell temperature of the battery in the vehicle.

[0059] The current cell temperature refers to the real-time collected cell temperature. Based on the current cell temperature, it can be determined whether the battery needs to be heated at a low temperature.

[0060] For example, a battery (i.e., a battery pack) is composed of multiple individual cells. The battery management system can collect the cell temperatures of these individual cells in real time and use the temperature of the cell with the lowest temperature (i.e., the lowest cell temperature) as the current cell temperature.

[0061] S202, when the current cell temperature is lower than the first temperature threshold, firstly, the battery is intermittently discharged in the first mode, and then intermittently discharged in the second mode, so as to raise the battery temperature.

[0062] Specifically, after obtaining the current cell temperature of the battery, the battery management system determines whether the current cell temperature is lower than the first temperature threshold. If the current cell temperature is lower than the first temperature threshold, the battery is first intermittently discharged in the first mode, and then intermittently discharged in the second mode to raise the battery temperature.

[0063] The first temperature threshold is used as a critical temperature value to determine whether the battery is in a low-temperature environment and requires the initiation of a low-temperature heating phase. For example, the first temperature threshold can be 10°C. It should be noted that the first temperature threshold can be set according to actual needs or experimental data; the value of the first temperature threshold is not specifically limited in this embodiment.

[0064] It should be noted that, in some embodiments, intermittent discharge of the battery refers to the battery periodically outputting current and being in a static state between two discharges, that is, the battery cycles through discharge-static.

[0065] In this embodiment, after the vehicle is successfully connected to the charging pile, when the current cell temperature of the battery in the vehicle is lower than a first temperature threshold, the battery is first intermittently discharged in a first mode, and then intermittently discharged in a second mode. In this way, under low-temperature conditions, intermittent discharge in the first mode causes the battery's inherent high polarization resistance and ohmic resistance to generate Joule heat and electrochemical polarization heat under pulsed current, achieving internal self-heating of the battery and increasing its temperature rise rate. Furthermore, intermittent discharge avoids the risk of lithium plating on the negative electrode caused by charging at low temperatures, improving battery safety under low-temperature conditions while ensuring a high temperature rise rate. In addition, intermittent discharge in the first mode also allows for the slow release of battery energy as the battery temperature rises.

[0066] Furthermore, after running the first mode, intermittently discharging the battery in the second mode can prevent the battery from becoming too low in power, avoid over-discharge, and extend the battery's lifespan.

[0067] In some examples, in the first mode (i.e., real-time control mode), the battery's discharge rate varies with the cell temperature. In the second mode (i.e., pulse heating mode), the battery's discharge rate is a first discharge rate; and the first discharge rate is greater than or equal to the battery's maximum discharge rate in the first mode.

[0068] In other words, when the current cell temperature is below the first temperature threshold, the system enters a low-temperature heating phase. During this phase, the battery is first intermittently discharged in a first mode. Specifically, during this intermittent discharge in the first mode, the current cell temperature is monitored in real time, and the discharge rate is increased as the cell temperature rises. Then, the battery is intermittently discharged in a second mode. Specifically, the battery is controlled to discharge intermittently according to the first discharge rate.

[0069] For example, in the first mode, the battery discharge rate can range from 6C to 10C. In the second mode, the first discharge rate can be either 10C or 12C.

[0070] In this embodiment, in the first mode, the battery discharge rate is adjusted according to the cell temperature change, ensuring both battery heating efficiency and the safety of low-temperature battery heating, thus avoiding damage to the battery. In the second mode, a larger initial discharge rate is used to control the battery for intermittent discharge, which can further improve the battery heating rate and shorten the battery heating time.

[0071] In some embodiments, the current cell temperature of the battery is acquired in real time throughout the low-temperature heating phase, and the battery is charged according to the charging parameters when the current cell temperature of the battery meets the sixth preset condition.

[0072] The sixth preset condition is the exit condition for the low-temperature heating stage, which is used to determine whether the battery temperature has risen to a higher range that meets the requirements for normal charging.

[0073] For example, the current cell temperature may include a minimum cell temperature and a maximum cell temperature. The minimum cell temperature is the cell temperature of the individual cell with the lowest temperature among multiple individual cells. The maximum cell temperature is the cell temperature of the individual cell with the highest temperature among multiple individual cells. Correspondingly, the sixth preset condition may be that the minimum cell temperature is greater than a third temperature threshold, and / or that the maximum cell temperature is greater than a fourth temperature threshold, wherein the fourth temperature threshold is greater than the third temperature threshold.

[0074] For example, the third temperature threshold can be 15°C. The fourth temperature threshold can be 35°C. It should be noted that the values ​​of the above temperature thresholds can be set according to actual needs or experimental data, and this embodiment does not impose specific limitations on them.

[0075] Specifically, during the low-temperature heating phase (i.e., the process of heating the battery at low temperatures), the battery management system collects the cell temperatures of multiple individual cells in real time and determines the minimum and maximum cell temperatures based on the individual cell temperatures. If the minimum cell temperature exceeds a third temperature threshold and / or the maximum cell temperature exceeds a fourth temperature threshold, it indicates that the battery temperature has risen to a higher range that meets the requirements for normal charging. At this point, intermittent discharge of the battery is stopped, i.e., the low-temperature heating phase ends, and the battery enters normal charging mode.

[0076] In normal charging mode, the battery can be charged according to the charging parameters. These parameters include the battery's maximum permissible charge / discharge power and maximum permissible charge / discharge current. The maximum permissible charge / discharge power limits the maximum power threshold that the battery can withstand under the current temperature and state of charge, preventing the battery from operating under overload. The maximum permissible charge / discharge current limits the maximum current threshold that the battery can withstand under the current conditions, preventing damage to the battery due to overcurrent.

[0077] Charging parameters may also include the battery's (i.e., the battery pack's) protection voltage, such as the battery pack's maximum protection voltage and minimum protection voltage. The battery's protection voltage is used to limit the safe operating range of the battery pack's total voltage, preventing the entire battery pack from being overcharged or over-discharged.

[0078] Charging parameters may also include the protection voltage of individual cells, such as the maximum protection voltage and the minimum protection voltage of individual cells. The protection voltage of an individual cell is used to limit the safe operating range of the voltage of a single cell, preventing overcharging or over-discharging of the cell.

[0079] Specifically, before determining whether to initiate a low-temperature heating phase based on the current cell temperature of the battery, the method may include: after the vehicle connects to the charging pile via the charging gun, it interacts with the charging pile through a handshake message to confirm whether the charging pile supports the low-temperature pulse heating function. Simultaneously, the current battery temperature is acquired. If the current battery temperature is less than the fifth temperature threshold, it indicates that the vehicle is in a low-temperature environment, meaning the battery needs to be charged in this environment. At this point, the current charging parameters are acquired, i.e., the charging parameters for the low-temperature environment. These charging parameters may include the battery's maximum allowable charge / discharge power, maximum allowable charge / discharge current, battery protection voltage, and individual cell protection voltage. After acquiring the charging parameters for the low-temperature environment, the battery management system can send these parameters to the charging pile so that the charging pile can charge the battery based on these parameters. For example, the capacity of the power grid and energy storage cabinet can be allocated according to the charging parameters for the low-temperature environment.

[0080] In some examples, when the low-temperature pulse heating function of the charging pile is confirmed, the battery is heated at a low temperature based on the current cell temperature of the battery in the vehicle. That is, when the low-temperature pulse heating function of the charging pile is confirmed, the battery is heated at a low temperature when the current cell temperature is lower than a first temperature threshold.

[0081] In this embodiment, the battery is first heated at a low temperature. Once the battery temperature rises to a higher range that meets the requirements for normal charging, the battery is charged normally. This avoids lithium plating on the negative electrode caused by directly charging the battery with a large current in a low-temperature environment. Furthermore, charging the battery according to the charging parameters for a low-temperature environment can prevent abnormal conditions such as overvoltage and overcurrent, thus extending the battery's lifespan.

[0082] In some embodiments, the battery is intermittently discharged, specifically by controlling the battery to alternately discharge and charge. That is, after entering the low-temperature heating stage, the battery is first alternately discharged and charged in a first mode, and then alternately discharged and charged in a second mode.

[0083] Optionally, in the first mode (i.e., real-time control mode), the battery's discharge rate varies with the cell temperature. In the second mode (i.e., pulse heating mode), the battery's discharge rate is a first discharge rate; and the first discharge rate is greater than or equal to the battery's maximum discharge rate in the first mode.

[0084] In this embodiment, the battery is alternately discharged and charged in a low-temperature environment. During the discharge phase, the battery's ohmic internal resistance and electrochemical polarization resistance are utilized to generate Joule heat and polarization heat through a relatively high-rate current, achieving internal self-heating of the battery. During the charging phase, reverse charging at a relatively low rate eliminates concentration polarization and electrochemical polarization accumulated during discharge, alleviating lithium ion accumulation on the negative electrode surface. Through alternating discharge heat generation and charging depolarization, the battery can be rapidly heated at low temperatures while avoiding the risks of lithium plating on the negative electrode and over-discharge caused by continuous high-current discharge, thereby improving the safety and efficiency of low-temperature heating.

[0085] In some examples, in the first mode, the alternating discharge and charge process of the battery includes multiple first charge-discharge cycles, in which the battery is first discharged and then charged. The discharge rate of the battery in the first charge-discharge cycle is greater than the charge rate in the first charge-discharge cycle.

[0086] In the second mode, the battery's alternating discharge and charge process includes multiple second charge-discharge cycles. In each second charge-discharge cycle, the battery is first discharged, then charged. The discharge rate of the battery in the second charge-discharge cycle is equal to the charge rate of the second charge-discharge cycle, and the discharge duration of the battery in the second charge-discharge cycle is equal to the charging duration of the second charge-discharge cycle.

[0087] In this embodiment, in the first mode, by setting the discharge rate to be greater than the charging rate, the discharge stage uses a larger current to drive the battery's ohmic internal resistance and electrochemical polarization internal resistance to generate a large amount of Joule heat and polarization heat, thereby achieving rapid temperature rise in a low-temperature environment; the charging stage uses a lower reverse charging rate, which can effectively eliminate the concentration polarization and electrochemical polarization accumulated during the discharge process, and at the same time alleviate the deposition of lithium ions on the negative electrode surface, avoiding the risk of lithium plating on the negative electrode caused by charging with a large current in a low-temperature environment, thereby improving the safety of low-temperature heating while ensuring the initial heating efficiency.

[0088] Furthermore, in the second mode, by making the discharge rate equal to the charge rate and the discharge duration equal to the charging duration, the charge and discharge process achieves a balance, making the net discharge in each cycle approach zero, thus avoiding excessive consumption of battery power due to continuous heating. At the same time, the symmetrical charge and discharge mode can maintain stable current fluctuations and continuously generate Joule heat using the battery's internal resistance. Even in the low-power range, it can still maintain high-frequency pulse heat generation, effectively avoiding the risk of deep over-discharge and voltage breakdown caused by asymmetrical large discharge at low power levels, and ensuring the safety and sustainability of the later stages of low-temperature heating.

[0089] The following is a schematic illustration of the process of alternating discharge and charge of the battery in the first mode.

[0090] In this embodiment, in the first mode, the process of the battery alternately discharging and charging includes multiple first charge-discharge cycles. In each first charge-discharge cycle, the battery is first discharged and then charged.

[0091] The first charge-discharge cycle refers to the smallest cycle unit in which the battery performs one complete discharge operation and one complete reverse charge operation in the first mode. Each first charge-discharge cycle may include a discharge phase and a charging phase. For ease of explanation, the discharge phase of any charge-discharge cycle in the first mode (i.e., the first charge-discharge cycle) is referred to as the first discharge phase, and the corresponding charging phase is referred to as the first charging phase.

[0092] Here, discharge rate refers to the rate at which the battery outputs current during the discharge phase. Charge rate refers to the rate at which the battery receives current during the charging phase. For ease of explanation, the discharge rate during the discharge phase of a first charge-discharge cycle is referred to as the fourth discharge rate, and the discharge rate during the charging phase of a first charge-discharge cycle is referred to as the third charge rate.

[0093] Optionally, the discharge rate of the battery in the first charge-discharge cycle is greater than the charging rate in the first charge-discharge cycle, that is, for the same first charge-discharge cycle, the fourth discharge rate is greater than the third charging rate.

[0094] For example, the fourth discharge rate can be 8C and the third charge rate can be 5C. For example, the fourth discharge rate can be 6C and the third charge rate can be 3C.

[0095] Here, discharge duration refers to the duration of the battery's discharge phase within one cycle. Charging duration refers to the duration of the battery's charging phase within one cycle. For ease of explanation, the duration of the battery's discharge phase within a first charge-discharge cycle is called the first discharge duration, and the duration of the battery's charging phase within a first charge-discharge cycle is called the first charging duration.

[0096] Optionally, the discharge duration of the battery in the first charge-discharge cycle is greater than or equal to the charging duration in the first charge-discharge cycle, that is, for the same first charge-discharge cycle, the first discharge duration is greater than or equal to the first charging duration.

[0097] In practice, the battery management system controls the battery to perform multiple first charge-discharge cycles. In each first charge-discharge cycle, the battery is first controlled to discharge at a relatively high discharge rate to generate Joule heat using the battery's internal resistance; then the battery is controlled to reverse charge at a relatively low charge rate to eliminate the polarization generated during the discharge process.

[0098] In this embodiment, during the initial stage of low-temperature heating, the battery has sufficient charge. A higher fourth discharge rate is used to discharge the battery, rapidly generating Joule heat inside and increasing the battery's heating rate. Furthermore, a lower third charge rate is used to reverse charge the battery, quickly eliminating concentration polarization and electrochemical polarization, and mitigating lithium ion accumulation on the negative electrode surface. This ensures rapid battery heating while effectively avoiding the risks of lithium plating on the negative electrode and over-discharge caused by continuous high-current discharge at low temperatures, thus improving efficiency and safety during the initial stage of low-temperature heating.

[0099] In this embodiment, when the battery is alternately discharged and charged in the first mode, the discharge phase and the charging phase can be switched based on the change in cell voltage.

[0100] The following is a schematic illustration of the switching process between the discharge and charging phases in the first mode.

[0101] like Figure 3 As shown, the process of alternately discharging and charging the battery in the first mode may include:

[0102] S301, when performing the first discharge stage of the first charge-discharge cycle, if the current cell voltage of the battery drops to meet the first preset condition, then switch to the first charging stage of the first charge-discharge cycle.

[0103] In this embodiment, in the first mode, when the battery is in the discharge stage, it can be determined whether to switch to the charging stage based on the current cell voltage of the battery.

[0104] The current cell voltage refers to the real-time terminal voltage of the cell. The current cell voltage allows for switching between the discharge and charging phases.

[0105] For example, the current cell voltage may include the minimum cell voltage and the maximum cell voltage. The minimum cell voltage is the cell voltage of the individual cell with the lowest terminal voltage among a group of individual cells. The maximum cell voltage is the cell voltage of the individual cell with the highest terminal voltage among a group of individual cells.

[0106] The first preset condition is used to determine whether to switch from the discharge phase to the charging phase. For example, the first preset condition may be that the current cell voltage is less than a first voltage threshold. For example, the first preset condition may also be that the duration for which the current cell voltage is less than the first voltage threshold is greater than or equal to a second duration threshold. Wherein, when determining whether the first preset condition is met, the current cell voltage may be the minimum cell voltage.

[0107] For example, the first voltage threshold can be 1.5V. It should be noted that in practical applications, as shown in the above embodiments, when the vehicle is in a low-temperature environment (i.e., the current battery temperature is below the fifth temperature threshold), the vehicle can obtain the battery's protection voltage and the minimum protection voltage of a single cell under low-temperature conditions. Here, the first voltage threshold can be set based on the battery's protection voltage and the minimum protection voltage of a single cell under low-temperature conditions. For example, in a low-temperature environment, the minimum protection voltage of a single cell is 1.5V, and this minimum protection voltage of a single cell is used as the first voltage threshold.

[0108] For example, the second duration threshold can be 50ms or 100ms. It should be noted that the first voltage threshold and the second duration threshold can be set according to actual needs or experimental data. In this embodiment, the values ​​of the above thresholds are not specifically limited.

[0109] S302, when performing the first charging stage of the first charging and discharging cycle, if the current cell voltage of the battery meets the second preset condition, or if the duration of the first charging stage is greater than the first duration threshold, then switch to the first discharging stage of the next first charging and discharging cycle.

[0110] In this embodiment, in the first mode, when the battery is in the charging stage, it can be determined whether to switch to the discharging stage based on the current cell voltage of the battery or the duration of the current charging stage.

[0111] Determining whether the duration of the battery's current charging phase exceeds a first duration threshold can serve as a condition for deciding whether to switch from the charging phase to the discharging phase. For example, the first duration threshold can be 1 second. It should be noted that the first duration threshold can be set according to actual needs or experimental data; the values ​​of the aforementioned thresholds are not specifically limited in this embodiment.

[0112] The second preset condition is another condition used to determine whether to switch from the charging stage to the discharging stage. For example, the second preset condition may be that the current cell voltage is greater than a second voltage threshold. For example, the second preset condition may also be that the duration for which the current cell voltage is greater than the second voltage threshold is greater than or equal to a third duration threshold. Wherein, when determining whether the second preset condition is met, the current cell voltage may be the maximum cell voltage.

[0113] For example, the second voltage threshold can be 3.7V. It should be noted that in practical applications, as shown in the above embodiments, when the vehicle is in a low-temperature environment (i.e., the current battery temperature is below the fifth temperature threshold), the vehicle can obtain the battery's protection voltage and the minimum protection voltage of a single cell under low-temperature conditions. Here, the first voltage threshold can be set based on the battery's protection voltage and the maximum protection voltage of a single cell under low-temperature conditions. For example, in a low-temperature environment, the maximum protection voltage of a single cell is 3.7V, and this maximum protection voltage of a single cell is used as the second voltage threshold.

[0114] For example, the third duration threshold can be 50ms or 100ms. It should be noted that the second voltage threshold and the third duration threshold can be set according to actual needs or experimental data, and the values ​​of the above thresholds are not specifically limited in this embodiment.

[0115] In some embodiments, after the vehicle successfully connects to the charging pile, the vehicle interacts with the charging pile via a handshake message and sends the charging parameters for low-temperature environments to the charging pile. These charging parameters may include the battery's protection voltage and the protection voltage of individual battery cells (such as the maximum and minimum protection voltage of individual cells). Based on this, during the low-temperature heating process of the battery (i.e., the low-temperature heating stage), the charging pile can also obtain the current cell voltage of the battery, determine whether a discharge and charging switch is needed based on the current cell voltage, and send a corresponding switching command to the battery management system to instruct the battery management system to control the battery to switch between discharge and charging.

[0116] For example, in the first mode, when the battery is in the discharge stage, the charging pile can obtain the current cell voltage of the battery in real time. Based on the charging parameters under low temperature environment, the charging pile determines whether the current cell voltage of the battery meets the first preset condition. If the current cell voltage of the battery meets the first preset condition, it determines whether the battery should switch to the charging stage. If the battery does not switch to the charging stage, the charging pile sends a first switching instruction to the battery management system. The first switching instruction is used to instruct the battery management system to control the battery to switch from the discharge stage to the charging stage.

[0117] For example, in the first mode, when the battery is in the charging stage, the charging pile can obtain the current cell voltage of the battery in real time. Based on the charging parameters under low temperature environment, the charging pile determines whether the current cell voltage of the battery meets the second preset condition. At the same time, it can determine whether the duration of the battery in this charging stage is greater than the first duration threshold. If the current cell voltage of the battery meets the second preset condition and / or the duration of the battery in this charging stage is greater than the first duration threshold, it determines whether the battery should switch to the discharging stage. If the battery does not switch to the discharging stage, the charging pile sends a second switching instruction to the battery management system. The second switching instruction is used to instruct the battery management system to control the battery to switch from the charging stage to the discharging stage.

[0118] The following example illustrates the switching process between the discharge and charging phases in the first mode, using the current cell voltage (including the minimum and maximum cell voltages) as an example. The first preset condition is that the duration for which the current cell voltage (e.g., the minimum cell voltage) is less than a first voltage threshold is greater than or equal to a second duration threshold; the second preset condition is that the duration for which the current cell voltage (e.g., the maximum cell voltage) is greater than the second voltage threshold is greater than or equal to a third duration threshold.

[0119] In specific implementation, in the first mode, when discharging the battery (i.e., performing the first discharge stage within a first charge-discharge cycle), the minimum cell voltage of the battery is monitored in real time. If the minimum cell voltage drops to a first voltage threshold (e.g., 1.5V), and the duration for which the minimum cell voltage is less than the first voltage threshold reaches a second duration threshold (e.g., 100ms), then the minimum cell voltage meets the first preset condition, and the charging stage is switched.

[0120] When charging the battery (i.e., performing the first charging phase within a first charge-discharge cycle), the maximum cell voltage of the battery is monitored in real time. If the maximum cell voltage rises to the second voltage threshold (e.g., 3.7V) and the duration for which the maximum cell voltage is greater than or equal to the second voltage threshold reaches the third duration threshold (e.g., 100ms), the maximum cell voltage meets the second preset condition, and the battery switches to the discharge phase within the next first charge-discharge cycle.

[0121] Furthermore, while charging the battery, the charging duration of this charging phase is also timed simultaneously. If the charging duration of this charging phase exceeds the first duration threshold (i.e., the duration of the first charging phase exceeds the first duration threshold), then the system switches to the discharging phase in the next first charge-discharge cycle.

[0122] In this embodiment, closed-loop control of pulse charge / discharge switching is achieved through dual criteria of voltage boundary and duration. During the discharge phase, the current lowest single-cell voltage limit constraint prevents over-discharge and lithium deposition in the weakest cell; during the charging phase, the current highest single-cell voltage limit constraint prevents overcharging, and a first duration threshold constraint prevents polarization accumulation. The duration determination filters out sampling noise or transient voltage spikes, avoiding false triggering of switching, thereby achieving a dynamic balance between heat generation efficiency and safety boundaries, ensuring the high efficiency and reliability of the pulse heating process.

[0123] In some embodiments, during the intermittent discharge of the battery in the first mode, the current cell temperature is collected in real time, and the discharge rate of the battery is increased as the cell temperature rises.

[0124] Specifically, the process of alternating discharge and charge of the battery in the first mode includes a first control stage and a second control stage performed sequentially. The first control stage refers to the control stage during the initial stage of low-temperature heating. The second control stage refers to the control stage after the cell temperature rises.

[0125] like Figure 4 As shown, the process of alternately discharging and charging the battery in the first mode may include:

[0126] S401, execute the first control phase.

[0127] In this process, the discharge rate of the battery in the first control phase is the second discharge rate, and the charging rate of the battery in the first control phase is the first charging rate.

[0128] For example, the second discharge rate can be 8C or 6C. The first charge rate can be 5C.

[0129] S402, if the current cell temperature rises to the second temperature threshold, the system switches from the first control stage to the second control stage.

[0130] In this process, the battery discharge rate during the second control phase is the third discharge rate, and the battery charge rate during the second control phase is the second charge rate. The third discharge rate is greater than the second discharge rate, and the second charge rate is greater than or equal to the first charge rate.

[0131] For example, the third discharge rate can be 10C. The second charge rate can be 5C.

[0132] The second temperature threshold refers to the critical temperature point that triggers the switching of the control phase. The second temperature threshold is lower than the third temperature threshold in the exit condition of the low-temperature heating phase. For example, the second temperature threshold could be -20°C.

[0133] In practice, the first control phase is initially executed, during which the battery alternates between a second discharge rate and a first charge rate. The battery cell temperature is monitored in real time, and when the cell temperature rises to a second temperature threshold, the control strategy switches from the first control phase to the second control phase. In the second control phase, the discharge rate is increased to a third discharge rate, and the charge rate is adjusted to the second charge rate, continuing the alternating charge and discharge cycle.

[0134] In this embodiment, as the temperature rises, the activity of the electrolyte inside the battery increases and the internal resistance decreases. At this time, by switching to the second control stage and increasing the discharge rate, the Joule heating rate can be further accelerated, and the overall heating time can be shortened. At the same time, by correspondingly increasing or maintaining the charging rate, the increased discharge current can be matched to maintain an effective depolarization effect, thereby maximizing the battery's heating efficiency while ensuring battery safety.

[0135] The following is a schematic illustration of the process of alternating discharge and charge of the battery in the second mode.

[0136] In this embodiment, in the second mode, the process of alternating discharge and charge of the battery includes multiple second charge-discharge cycles. In each second charge-discharge cycle, the battery is first discharged and then charged.

[0137] The second charge / discharge cycle refers to the smallest cycle unit in which the battery performs one complete discharge operation and one complete reverse charge operation in the second mode. Each second charge / discharge cycle may include a discharge phase and a charging phase. For ease of explanation, the discharge phase of any charge / discharge cycle in the second mode (i.e., the second charge / discharge cycle) is referred to as the second discharge phase, and the corresponding charging phase is referred to as the second charging phase.

[0138] In the second mode, the battery discharge rate is the first discharge rate, and the battery charge rate is the fourth charge rate.

[0139] For ease of explanation, the duration of the battery in the discharge phase within a second charge-discharge cycle is called the second discharge duration, and the duration of the battery in the charging phase within a second charge-discharge cycle is called the second charging duration.

[0140] Optionally, the discharge rate of the battery in the second charge-discharge cycle is equal to the charge rate in the second charge-discharge cycle, and the discharge duration of the battery in the second charge-discharge cycle is equal to the charging duration in the second charge-discharge cycle. In other words,

[0141] For example, the first discharge rate is 10C. The fourth charge rate is 10C.

[0142] For example, the second discharge duration is 1 second. The second charging duration is 1 second.

[0143] In specific implementation, in the second mode, when discharging the battery (i.e., executing the second discharge phase within a second charge-discharge cycle), the duration of this discharge phase is timed. When the duration of this discharge phase reaches a preset duration threshold (e.g., 1 second), the system switches to the charging phase. When charging the battery (i.e., executing the second charging phase within a second charge-discharge cycle), the duration of this charging phase is timed. When the duration of this charging phase reaches a preset duration threshold (e.g., 1 second), the system switches to the discharging phase.

[0144] In this embodiment, the battery charge is already at a low level during the later stages of low-temperature heating. At this point, employing a symmetrical charge-discharge mode with equal rate and duration ensures that the net discharge of the battery in each cycle approaches zero, preventing further net consumption of battery power. Simultaneously, utilizing the polarization resistance of a high-rate pulse current (10C) to continuously generate Joule heat maintains high-frequency pulse heat generation without compromising the low-charge safety boundary. This effectively avoids the risks of deep over-discharge and voltage breakdown caused by continuous asymmetric large discharge at low charge levels, ensuring safety and sustainability during the later stages of low-temperature heating.

[0145] The alternating discharge and charging processes of the first and second modes have been explained above. The switching between the first and second modes is illustrated below.

[0146] In some embodiments, during the low-temperature heating stage, the current state of charge of the battery cells can be acquired in real time, and the first mode can be switched to the second mode based on the change in the current state of charge of the battery cells.

[0147] In some examples, the process of first controlling the battery to alternately discharge and charge in a first mode, and then alternating the discharge and charge in a second mode, may include: obtaining the current state of charge (SOC) of the battery cell when the current cell temperature is lower than a first temperature threshold; if the current SOC meets a third preset condition, then alternating the discharge and charge in the first mode; after running the first mode, re-obtaining the current SOC of the battery cell; if the re-obtained current SOC meets a fourth preset condition, then alternating the discharge and charge in the second mode.

[0148] The current state of charge (SOC) of the battery cells refers to the real-time data collected on the battery cells. Based on the current SOC, the appropriate low-temperature heating mode (such as mode one or mode two) can be determined.

[0149] For example, the battery management system can collect the state of charge (SOC) of multiple individual cells in real time, and take the SOC of the individual cell with the lowest SOC (i.e., the lowest SOC) as the current SOC.

[0150] The third preset condition is used to determine whether the battery's current state of charge is in a high range, in order to determine whether to enter the first mode.

[0151] For example, the third preset condition can be that the current state of charge is greater than the first state of charge threshold. For example, the third preset condition can also be that the duration for which the current state of charge is greater than the first state of charge threshold is greater than or equal to a fourth duration threshold.

[0152] For example, the first state of charge threshold can be 10% or 15%. For example, the fourth duration threshold can be 100ms. It should be noted that the first state of charge threshold and the fourth duration threshold can be set according to actual needs or experimental data, and the values ​​of the above thresholds are not specifically limited in this embodiment.

[0153] The fourth preset condition is used to determine whether the current state of charge of the battery has decayed to a lower range, so as to determine whether to switch from the first mode to the second mode.

[0154] For example, the fourth preset condition can be that the current state of charge is less than or equal to the first state of charge threshold. For example, the fourth preset condition can also be that the duration for which the current state of charge is less than or equal to the first state of charge threshold is greater than or equal to a fifth duration threshold.

[0155] For example, the fifth duration threshold can be 100ms. It should be noted that the fifth duration threshold can be set according to actual needs or experimental data, and the value of the fifth duration threshold is not specifically limited in this embodiment.

[0156] In practical applications, multiple first state of charge (SBC) thresholds can be set. After obtaining the current cell SBC, the first SBC threshold can be selected based on the accuracy of the current SBC. Specifically, the accuracy of the current SBC can be determined by whether it meets a preset accuracy requirement. If the current SBC meets the preset accuracy requirement, it indicates a high accuracy, and a smaller first SBC threshold, such as 10%, is selected. If the current SBC does not meet the preset accuracy requirement, it indicates a low accuracy and a certain deviation, and a larger first SBC threshold, such as 15%, is selected.

[0157] Specifically, after entering the low-temperature heating stage, the battery management system acquires the current state of charge (SOC) of the battery cells and determines whether the current SOC meets the third preset condition. If the current SOC meets the third preset condition, the battery is alternately discharged and charged in the first mode. Simultaneously, during the operation of the first mode, the current SOC of the battery cells is acquired in real time. When the current SOC decreases to meet the fourth preset condition, indicating that the battery's charge is in a low range, the first mode is switched to the second mode, and the battery is alternately discharged and charged in the second mode.

[0158] It should be noted that the specific implementation methods for alternating battery discharge and charging in the first mode and the specific implementation methods for alternating battery discharge and charging in the second mode can be found in the above embodiments, and will not be repeated here.

[0159] In this embodiment, as the low-temperature heating proceeds, the battery power is gradually depleted. By monitoring the current state of charge (SOC) of the cells in real time and introducing multi-level threshold judgments, the control mode switching can be precisely triggered based on the actual battery power decay state, avoiding the over-discharge risk caused by performing asymmetric large discharge in the low-charge range. Simultaneously, the SOC threshold for triggering switching is dynamically adjusted according to the different accuracy of the SOC estimation, which can accommodate the control accuracy requirements under different operating conditions and avoid premature or delayed exit due to estimation errors. This achieves an adaptive balance between heating efficiency and battery safety boundaries, improving the robustness and safety of the heating control strategy.

[0160] In some embodiments, after running the first mode, the method further includes: if the duration of the discharge phase in the first mode meets a fifth preset condition, then the battery is alternately discharged and charged in the second mode.

[0161] The fifth preset condition is that, in a consecutive preset number of first charge-discharge cycles, the duration of the discharge phase in each first charge-discharge cycle is greater than the sixth duration threshold.

[0162] For example, the sixth duration threshold can be 2 seconds. The preset number can be 2.

[0163] Specifically, when the battery management system alternately charges and discharges the battery in the first mode, it counts the duration of the first discharge phase in each first charge-discharge cycle in real time. If the duration of the first discharge phase is greater than the sixth duration threshold (e.g., 2 seconds) in a consecutive preset number of first charge-discharge cycles (e.g., 2), it is determined that the fifth preset condition is met, and the battery is controlled to switch from the first mode to the second mode, and the battery is alternately discharged and charged in the second mode.

[0164] In this embodiment, during the initial stage of low-temperature heating, the battery's internal resistance is extremely high, and high-rate discharge will instantly pull down the terminal voltage, resulting in a short discharge duration. As the first mode progresses, the battery generates Joule heat, the temperature gradually increases, and the internal resistance gradually decreases, allowing the discharge phase to last longer before triggering the lower voltage limit. Therefore, a discharge duration exceeding the sixth duration threshold consecutively indicates that the battery has significantly heated up and its internal resistance has decreased substantially. By triggering mode switching based on this condition, the battery's heating state can be accurately identified, and the second mode can be switched to promptly after achieving the heating objective of the first mode, avoiding unnecessary asymmetric high-rate discharge. This ensures heating efficiency while improving the accuracy and safety of the control strategy.

[0165] In some embodiments, after running the first mode, the method further includes: if the target cell voltage in the first mode is less than a third voltage threshold, then alternately discharging and charging the battery in a second mode.

[0166] The target cell voltage is the cell voltage at the end of the charging phase of any first charge-discharge cycle.

[0167] For example, the third voltage threshold can be 2.5V.

[0168] Specifically, during the alternating charging and discharging of the battery in the first mode, the battery management system acquires the current cell voltage of the battery in real time at the end of each first charging phase as the target cell voltage (e.g., the minimum cell voltage). If the target cell voltage is less than a third voltage threshold (e.g., 2.5V), the battery is immediately controlled to exit the first mode and switch to the second mode, in which the battery is alternately discharged and charged.

[0169] In this embodiment, under normal circumstances, the battery's terminal voltage should recover somewhat after reverse charging. If the cell voltage is still less than the third voltage threshold after the charging phase ends, it indicates that the battery is close to a deep discharge state, or that low temperature and deep discharge have caused severe negative electrode polarization that cannot be effectively alleviated by short-term charging. If the battery continues to enter the next cycle of high-rate discharge in this state, the battery voltage will instantly drop below 0V, causing irreversible damage such as lithium plating on the negative electrode or even dissolution of the copper current collector. By triggering forced exit under this condition, extreme over-discharge and polarization failure protection can be provided, safeguarding the battery's safety baseline and improving the reliability of the low-temperature heating process.

[0170] In other words, the exit conditions for Mode 1 include at least one of the following:

[0171] The current state of charge of the battery cell has decreased to meet the fourth preset condition;

[0172] The duration of the discharge phase in the first mode meets the fifth preset condition.

[0173] The target cell voltage in the first mode is less than the third voltage threshold.

[0174] In some embodiments, the method further includes: after entering the low-temperature heating stage, if the current state of charge of the battery cell does not meet the third preset condition, the battery is directly discharged and charged alternately in the second mode.

[0175] In this embodiment, when the current battery charge is low (i.e., the third preset condition is not met), the first mode (asymmetric high-rate discharge mode) is skipped directly. This effectively avoids excessive consumption of the battery's net charge caused by the discharge rate exceeding the charging rate in the first mode, preventing the risk of deep over-discharge and voltage breakdown caused by a sharp drop in charge during the initial heating phase. Simultaneously, switching directly to the second mode for symmetrical charge and discharge utilizes the battery's internal resistance to continuously generate Joule heat for self-heating, with the net discharge rate in each cycle approaching zero. This ensures the smooth operation of the low-temperature heating function while maximizing battery charge balance, improving the adaptability of the heating strategy to different initial charge states and enhancing safety under boundary conditions.

[0176] In some embodiments, during the low-temperature heating phase, the battery can be detected as abnormal. If the battery is detected to be in an abnormal state, the low-temperature heating phase is terminated.

[0177] For example, during the low-temperature heating stage, the cell voltage of each individual cell in the battery is acquired, and the minimum cell voltage is determined based on the cell voltage of each individual cell; and the cell temperature difference is determined based on the temperature of different detection points, which can characterize the maximum difference in cell temperature between different cells; if the minimum cell voltage is less than a first voltage threshold (minimum protection voltage of an individual cell) and the cell temperature difference is greater than a preset temperature difference threshold, then the low-temperature heating of the battery is stopped, that is, the low-temperature heating stage is exited.

[0178] In this embodiment, the sudden drop in the minimum voltage of a single cell and the rapid increase in the temperature difference between cells are used as the joint criteria for determining thermal runaway. This avoids the false triggering of a single indicator due to large polarization voltage drop or uneven heating during low-temperature pulse heating, ensuring the continuity of the heating process. It can also accurately identify early signs of thermal runaway that may be accompanied by local short circuits. While ensuring the efficiency of low-temperature heating, it safeguards the last line of battery safety and greatly improves the reliability and safety of the vehicle's low-temperature heating solution.

[0179] The following example illustrates the low-temperature heating process of a battery, taking the current cell temperature as the lowest cell temperature and the current cell state of charge as the lowest cell state of charge.

[0180] After the battery management system detects that the vehicle has successfully connected to the charging station, it obtains the current lowest cell temperature of the battery (i.e., T). minThe system determines whether the lowest temperature of the battery cell is lower than a first temperature threshold (e.g., 10°C). If the lowest temperature of the battery cell is lower than the first temperature threshold, the system enters the low-temperature heating stage.

[0181] After entering the low-temperature heating stage, the first step is to obtain the battery cell's lowest state of charge (SOC). min The system determines whether the lowest state of charge of the battery cell is greater than the first state of charge threshold (e.g., 10%), and whether the duration of the lowest state of charge of the battery cell being greater than the first state of charge threshold reaches the fourth duration threshold (e.g., 100ms). If the duration of the lowest state of charge of the battery cell being greater than the first state of charge threshold reaches the fourth duration threshold, the system enters the first mode.

[0182] like Figure 5 As shown, after entering the first mode, the first control phase is executed first, during which the battery is alternately discharged and charged. Specifically, the battery management system controls the battery to discharge at a second discharge rate (e.g., 6C) and to charge at a first charge rate (e.g., 5C). Simultaneously, the minimum cell temperature is collected in real time. If the minimum cell temperature rises to a second temperature threshold (e.g., -20℃), the system switches from the first control phase to the second control phase. In the second control phase, the battery management system controls the battery to discharge at a third discharge rate (e.g., 10C) and to charge at a second charge rate (e.g., 5C). Furthermore, during the execution of the first mode, the current cell voltage (e.g., minimum and maximum cell voltage) is acquired in real time, and the discharge and charging phases are switched based on the current cell voltage.

[0183] During the operation of the first mode, it is determined whether the exit conditions of the first mode are met. The exit conditions of the first mode include at least one of the following: Condition 1: The current state of charge of the battery cell decreases to meet the fourth preset condition; Condition 2: The duration of the discharge phase in the first mode meets the fifth preset condition; Condition 3: The target battery cell voltage in the first mode is less than the third voltage threshold.

[0184] If the exit conditions for the first mode are met, the first mode will be switched to the second mode (i.e., symmetrical charge / discharge mode). In the second mode, the battery alternately discharges and charges, which includes multiple second charge / discharge cycles. In each second charge / discharge cycle, the battery is first discharged, then charged. The discharge rate of the battery in the second charge / discharge cycle is equal to the charge rate of the second charge / discharge cycle, and the discharge duration of the battery in the second charge / discharge cycle is equal to the charging duration of the second charge / discharge cycle. For example, in the second mode, the battery management system controls the battery to discharge at a first discharge rate (e.g., 10C) and controls the battery to charge at a fourth charge rate (e.g., 10C).

[0185] During the low-temperature heating process, to avoid false alarms caused by drastic changes in current and voltage, some fault detections need to be shielded. For example, overcurrent faults during charging and discharging can be shielded. For instance, parameters can be adjusted synchronously based on the thresholds set above, retaining the highest level of functional safety overcurrent faults to avoid affecting vehicle operation during the battery's low-temperature heating phase. Similarly, undervoltage faults can be shielded. For instance, parameters can be adjusted synchronously based on the thresholds set above, retaining the highest level of functional safety undervoltage faults to avoid affecting vehicle operation during the battery's low-temperature heating phase. Insulation detection can also be shielded.

[0186] In addition, after entering the low-temperature heating stage, if the currently collected minimum state of charge of the cell is less than or equal to the first state of charge threshold, or if the duration for which the minimum state of charge of the cell is greater than the first state of charge threshold does not reach the fourth duration threshold (i.e., the currently collected minimum state of charge of the cell does not meet the third preset condition), the battery will be directly discharged and charged alternately in the second mode.

[0187] Finally, during the entire low-temperature heating phase, the current cell temperature of the battery (such as the minimum cell temperature and the maximum cell temperature) is obtained in real time. If the minimum cell temperature is greater than the third temperature threshold (such as 15°C), or the maximum cell temperature is greater than the fourth temperature threshold (such as 35°C), it indicates that the battery temperature meets the charging temperature requirements. At this time, the low-temperature heating phase is exited, and the battery is charged according to the charging parameters, that is, it enters the normal charging mode.

[0188] In addition, during the entire low-temperature heating stage, the cell voltage of each individual cell in the battery is acquired, and the minimum cell voltage is determined based on the cell voltage of each individual cell; and the cell temperature difference is determined based on the temperature of different detection points; if the minimum cell voltage is less than the first voltage threshold (minimum protection voltage of individual cell) and the cell temperature difference is greater than the preset temperature difference threshold, then the low-temperature heating of the battery is stopped, that is, the low-temperature heating stage is exited.

[0189] This application also provides a battery heating device, which is configured in a vehicle. Figure 6 As shown, the battery heating device 60 includes an acquisition module 601 and a control module 602. The acquisition module 601 acquires the current cell temperature of the battery in the vehicle after successful connection with the charging pile. The control module 602, when the current cell temperature is lower than a first temperature threshold, first intermittently discharges the battery in a first mode, then intermittently discharges the battery in a second mode to raise the battery temperature.

[0190] In some embodiments, in a first mode, the battery discharge rate varies with the cell temperature; in a second mode, the battery discharge rate is a first discharge rate; the first discharge rate is greater than or equal to the battery's maximum discharge rate in the first mode.

[0191] In some embodiments, the control module 602 is specifically configured to first alternately discharge and charge the battery in a first mode, and then alternately discharge and charge the battery in a second mode.

[0192] In some embodiments, in the first mode, the process of the battery alternately discharging and charging includes multiple first charge-discharge cycles. In each first charge-discharge cycle, the battery is first discharged and then charged. The discharge rate of the battery in the first charge-discharge cycle is greater than the charging rate in the first charge-discharge cycle.

[0193] In the second mode, the process of alternating discharge and charge of the battery includes multiple second charge-discharge cycles. In each second charge-discharge cycle, the battery is first discharged and then charged. The discharge rate of the battery in the second charge-discharge cycle is equal to the charging rate in the second charge-discharge cycle, and the discharge duration of the battery in the second charge-discharge cycle is equal to the charging duration in the second charge-discharge cycle.

[0194] In some embodiments, each first charge-discharge cycle includes a first discharge phase and a first charge phase. The control module 602 is specifically configured to: when executing the first discharge phase of the first charge-discharge cycle, if the current cell voltage of the battery meets a first preset condition, switch to the first charge phase of the first charge-discharge cycle; when executing the first charge phase of the first charge-discharge cycle, if the current cell voltage of the battery meets a second preset condition, or if the duration of the first charge phase is greater than a first duration threshold, switch to the first discharge phase of the next first charge-discharge cycle.

[0195] In some embodiments, the first preset condition includes at least one of the following: the current cell voltage is less than a first voltage threshold; the duration for which the current cell voltage is less than the first voltage threshold is greater than or equal to a second duration threshold.

[0196] The second preset condition includes at least one of the following: the current cell voltage is greater than the second voltage threshold; the duration for which the current cell voltage is greater than the second voltage threshold is greater than or equal to the third duration threshold.

[0197] In some embodiments, the process of alternately discharging and charging the battery in a first mode includes a first control phase and a second control phase performed sequentially. The control module 602 is specifically configured to: execute the first control phase, wherein the battery discharge rate in the first control phase is a second discharge rate, and the battery charge rate in the first control phase is a first charge rate; if the current cell temperature rises to a second temperature threshold, the system switches from the first control phase to the second control phase, wherein the battery discharge rate in the second control phase is a third discharge rate, and the battery charge rate in the second control phase is a second charge rate, the third discharge rate is greater than the second discharge rate, and the second charge rate is greater than or equal to the first charge rate.

[0198] In some embodiments, the control module 602 is specifically configured to: acquire the current state of charge of the battery cells; if the current state of charge of the battery cells meets a third preset condition, then alternately discharge and charge the battery in a first mode; after running the first mode, reacquire the current state of charge of the battery cells; if the reacquired current state of charge of the battery cells meets a fourth preset condition, then alternately discharge and charge the battery in a second mode.

[0199] In some embodiments, the third preset condition includes at least one of the following: the current state of charge of the battery cell is greater than the first state of charge threshold; the duration for which the current state of charge of the battery cell is greater than the first state of charge threshold is greater than or equal to a fourth duration threshold.

[0200] The fourth preset condition includes at least one of the following: the current state of charge of the battery cell is less than or equal to the first state of charge threshold; the duration during which the current state of charge of the battery cell is less than or equal to the first state of charge threshold is greater than or equal to the fifth duration threshold.

[0201] In some embodiments, in the first mode, the process of alternating discharge and charge of the battery includes multiple first charge-discharge cycles. After running the first mode, the control module 602 is further configured to: if the duration of the discharge phase in the first mode meets a fifth preset condition, then alternately discharge and charge the battery in the second mode; wherein, the fifth preset condition is that in a consecutive preset number of first charge-discharge cycles, the duration of the discharge phase in each first charge-discharge cycle is greater than a sixth duration threshold; or, if the target cell voltage in the first mode is less than a third voltage threshold, then alternately discharge and charge the battery in the second mode; wherein, the target cell voltage is the cell voltage at the end of the charging phase in any first charge-discharge cycle.

[0202] In some embodiments, after obtaining the current state of charge of the battery cells, the control module 602 is further configured to: if the current state of charge of the battery cells does not meet the third preset condition, then alternately discharge and charge the battery in a second mode.

[0203] The vehicle provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0204] Figure 7 This is a structural diagram of the vehicle provided in this application. Figure 7 As shown, the vehicle 70 provided in this embodiment includes at least one processor 701 and a memory 702. Optionally, the vehicle 70 also includes a communication component 703. The processor 701, memory 702, and communication component 703 are connected via a bus 704.

[0205] In a specific implementation, at least one processor 701 executes computer execution instructions stored in memory 702, causing at least one processor 701 to perform the above-described method.

[0206] The specific implementation process of processor 701 can be found in the above method embodiments, and its implementation principle and technical effect are similar. It will not be repeated here.

[0207] In the above embodiments, it should be understood that the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor.

[0208] The memory may include random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage device.

[0209] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.

[0210] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.

[0211] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method.

[0212] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0213] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components in the device.

[0214] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0215] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0216] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0217] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0218] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0219] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A battery heating method, characterized in that, The method includes: After the vehicle is successfully connected to the charging station, the current cell temperature of the battery in the vehicle is obtained. If the current cell temperature is lower than a first temperature threshold, the battery is first intermittently discharged in a first mode, and then intermittently discharged in a second mode, so as to raise the temperature of the battery.

2. The method according to claim 1, characterized in that, In the first mode, the discharge rate of the battery varies with the cell temperature; in the second mode, the discharge rate of the battery is a first discharge rate. The first discharge rate is greater than or equal to the maximum discharge rate of the battery in the first mode.

3. The method according to claim 1 or 2, characterized in that, The step of first intermittently discharging the battery in a first mode, and then intermittently discharging the battery in a second mode, includes: The battery is first alternately discharged and charged in the first mode, and then alternately discharged and charged in the second mode.

4. The method according to claim 3, characterized in that, In the first mode, the process of the battery alternating between discharging and charging includes multiple first charge-discharge cycles. In each first charge-discharge cycle, the battery is first discharged and then charged. The discharge rate of the battery in the first charge-discharge cycle is greater than the charging rate in the first charge-discharge cycle. In the second mode, the process of the battery alternating between discharging and charging includes multiple second charge-discharge cycles. In each second charge-discharge cycle, the battery is first discharged and then charged. The discharge rate of the battery in the second charge-discharge cycle is equal to the charging rate in the second charge-discharge cycle, and the discharge duration of the battery in the second charge-discharge cycle is equal to the charging duration in the second charge-discharge cycle.

5. The method according to claim 4, characterized in that, Each first charge-discharge cycle includes a first discharge phase and a first charge phase, wherein alternating discharge and charge of the battery in the first mode includes: When performing the first discharge phase of the first charge-discharge cycle, if the current cell voltage of the battery meets the first preset condition, then switch to the first charging phase of the first charge-discharge cycle. During the first charging phase of the first charge-discharge cycle, if the current cell voltage of the battery meets the second preset condition, or if the duration of the first charging phase is greater than the first duration threshold, then the cycle switches to the first discharging phase of the next first charge-discharge cycle.

6. The method according to claim 5, characterized in that, The first preset condition includes at least one of the following: The current cell voltage is less than a first voltage threshold; The duration during which the current cell voltage is less than the first voltage threshold is greater than or equal to the second duration threshold. The second preset condition includes at least one of the following: The current cell voltage is greater than the second voltage threshold; The duration during which the current cell voltage is greater than the second voltage threshold is greater than or equal to the third duration threshold.

7. The method according to claim 3, characterized in that, The process of alternately discharging and charging the battery in the first mode includes a first control phase and a second control phase performed sequentially; the alternating discharge and charge of the battery in the first mode includes: The first control phase is executed, wherein the discharge rate of the battery in the first control phase is a second discharge rate, and the charging rate of the battery in the first control phase is a first charging rate. If the current cell temperature rises to the second temperature threshold, the system switches from the first control stage to the second control stage. In the second control stage, the discharge rate of the battery is the third discharge rate, and the charging rate of the battery is the second charging rate. The third discharge rate is greater than the second discharge rate, and the second charging rate is greater than or equal to the first charging rate.

8. The method according to claim 3, characterized in that, The step of first alternately discharging and charging the battery in the first mode, and then alternately discharging and charging the battery in the second mode, includes: Obtain the current state of charge of the battery cells; If the current state of charge of the battery cell meets the third preset condition, then the battery is alternately discharged and charged in the first mode; After running the first mode, the current cell state of charge of the battery is reacquired; If the current state of charge of the battery cell is reacquired and meets the fourth preset condition, then the battery is alternately discharged and charged in the second mode.

9. The method according to claim 8, characterized in that, The third preset condition includes at least one of the following: The current state of charge of the battery cell is greater than the first state of charge threshold. The duration during which the current state of charge of the battery cell is greater than the first state of charge threshold is greater than or equal to the fourth duration threshold. The fourth preset condition includes at least one of the following: The current state of charge of the battery cell is less than or equal to the first state of charge threshold. The duration during which the current state of charge of the battery cell is less than or equal to the first state of charge threshold is greater than or equal to the fifth duration threshold.

10. The method according to claim 8, characterized in that, In the first mode, the process of the battery alternately discharging and charging includes multiple first charge-discharge cycles; After running the first mode, the method further includes: If the duration of the discharge phase in the first mode meets the fifth preset condition, then the battery is alternately discharged and charged in the second mode; wherein, the fifth preset condition is that in a consecutive preset number of first charge-discharge cycles, the duration of the discharge phase in each first charge-discharge cycle is greater than the sixth duration threshold. or, If the target cell voltage in the first mode is less than the third voltage threshold, then the battery is alternately discharged and charged in the second mode; wherein the target cell voltage is the cell voltage at the end of the charging phase of any first charge-discharge cycle.

11. The method according to claim 8, characterized in that, After obtaining the current cell state of charge of the battery, the method further includes: If the current state of charge of the battery cell does not meet the third preset condition, the battery is alternately discharged and charged in the second mode.

12. A battery heating device, characterized in that, include: The acquisition module is used to acquire the current cell temperature of the battery in the vehicle after the vehicle is successfully connected to the charging pile. The control module is configured to, when the current cell temperature is less than a first temperature threshold, first intermittently discharge the battery in a first mode, and then intermittently discharge the battery in a second mode, so as to raise the temperature of the battery.

13. A vehicle, characterized in that, include: Memory, processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory, causing the processor to perform the method as described in any one of claims 1-11.

14. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the method as described in any one of claims 1-11.

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