Charging and heating device and method for lithium battery at low temperature

Abstract

This invention relates to a charging and heating device and method for lithium batteries at low temperatures. The method involves acquiring the battery's temperature and state information; using temperature as the primary feature distinction and state information as a secondary feature distinction to generate a decision tree; iteratively optimizing the decision tree to obtain and execute the charging and heating judgment conditions; and after the battery is fully charged, obtaining a set heat preservation range for the fully charged battery and maintaining the battery temperature within this range. This invention provides fast and safe low-temperature charging of battery packs, improves the charging heater to save energy, and is convenient for users.

Description

Technical Field

[0001] The present invention relates to the field of battery charging and heating, and particularly to a charging and heating device and method for lithium batteries at low temperatures. Background Art

[0002] Whether it is a lithium iron phosphate battery or a ternary battery, direct charging and discharging at low temperatures will cause great damage to the battery, so heating treatment is often required.

[0003] In the current lithium battery charging and heating solutions, the heating stops after charging ends. After a period of time, when the battery needs to be discharged, it is again in a low-temperature condition. Using it in a low-temperature environment causes great damage to the battery and will greatly reduce the cycle life. However, heating before discharging will delay the usage time and cause inconvenience. In order to enable lithium battery products to charge safely and quickly at low temperatures and be able to discharge safely and quickly during the next use, there is an urgent need for a charging heater and charging and heating method for lithium batteries at low temperatures. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above technical deficiencies, and provide a charging and heating device and method for lithium batteries at low temperatures, so as to solve the technical problem in the prior art that lithium batteries are only heated during the charging process, resulting in the discharge still being in a low-temperature state.

[0005] To achieve the above technical purpose, the technical solution of the present invention provides a charging and heating method for lithium batteries at low temperatures, including the following steps:

[0006] Obtain the temperature and state information of the battery; use the temperature as the main feature discrimination condition and the state information as the secondary feature discrimination condition to generate a decision tree; through iterative optimization of the decision tree, obtain the judgment condition for charging and heating and execute it; after the battery charging is completed, obtain the set heat preservation range after the battery is fully charged, and perform heat preservation on the battery within the set heat preservation range.

[0007] Further, the state information further includes the SOC, SOH, charging method, and usage scenario of the battery.

[0008] Further, when the usage scenario is charging the battery to full charge, set temperature thresholds T1, T2, T3, and T4 from low to high, and the judgment condition for charging and heating is:

[0009] When the battery temperature T0 ≤ T1, do not charge and do not heat; when T1 < T0 < T2, only perform heating; when T2 ≤ T0 < T3, perform heating and charging simultaneously; when T3 ≤ T0 < T4, stop heating and only perform charging; when T0 ≥ T4, stop charging.

[0010] Furthermore, in the application scenario of charging the battery to half charge, the determination condition for charging heating is as follows: by comparing the battery's SOC value with a preset value, if the SOC value is ≥ the preset value, the battery charging heating process is directly ended; if the SOC value is < the preset value, the charging heating process is started until the battery is charged to the preset capacity, and then the charging heating process ends.

[0011] Furthermore, the step of obtaining the set insulation range after the battery is fully charged and insulating the battery within the set insulation range specifically includes: disconnecting the charging circuit after the battery pack is fully charged; obtaining the set insulation range according to the setting of the insulation function; and maintaining the actual battery temperature within the set insulation range through the heating circuit.

[0012] Furthermore, the heat preservation function can be set in three ways: the system default one-click setting, the user-defined numerical input setting, and the intelligent temperature setting.

[0013] Furthermore, the specific steps involved in training the intelligent temperature setting temperature data include:

[0014] Given a training set D and a continuous attribute temperature a, where a has n distinct values ​​in D, first sort them in ascending order, denoted as {a}. 1 ,a 2 ,…,a n Discretize the continuous temperature data by dividing it into points t, and obtain a set of n-1 candidate dividing points T.

[0015] Gain(D,a,t) is the information gain Gain after bisecting the sample set D based on the partition point t. ) The optimal dividing point Gain(D, a) is obtained, and the two optimal dividing points determined by adjacent intervals are selected as the two critical values ​​at both ends of the intelligent temperature range.

[0016] This invention also provides a technical solution for a lithium battery charging and heating device at low temperatures, comprising a data acquisition module, a BMS chip, a heating relay, a heating module, a charging relay, a charging module, and a power input module; wherein, the data acquisition module is electrically connected to the BMS chip and is used to acquire relevant characteristic differentiation conditions of the battery; the power input module, heating relay, heating module, and battery are connected to form a heating circuit; the power input module, charging relay, charging module, and battery are connected to form a charging circuit; the heating circuit and charging circuit are used to heat and charge the battery, respectively; the power input module is also connected to the BMS chip for power supply; the BMS chip is used to receive relevant characteristic differentiation conditions, obtain the judgment conditions for charging and heating based on the relevant characteristic differentiation conditions, and issue commands to control the opening and closing states of the charging relay and the heating relay; the charging and heating device is used in the above-mentioned charging and heating method.

[0017] Furthermore, it also includes a one-key setting module, a value setting module, and a status display module that are electrically connected to the BMS chip; wherein, the one-key setting module is used to select the system's default heat preservation range in heat preservation mode; the value setting module is used for users to set the heat preservation range themselves; and the status display module is used to display the status information of battery charging and heating.

[0018] Furthermore, the BMS chip electrical connection abnormality handling module is used to handle abnormal situations during the charging and heating process.

[0019] Compared with the prior art, the beneficial effects of the present invention include:

[0020] This invention proposes a charging and heating device and method for lithium batteries at low temperatures. Based on this, a decision tree algorithm is introduced, which can intuitively display the decision-making process at different stages in terms of time and decision sequence. When applied to complex multi-stage decision-making, the stages are clear and the hierarchy is well-defined, facilitating collective research by the decision-making body and allowing for thorough consideration of various factors, thus contributing to correct decision-making. This invention can quickly and safely charge battery packs at low temperatures, and the improved charging heater saves energy while also being user-friendly.

[0021] Furthermore, this invention establishes selection features based on the information gain of the judgment conditions of each process. The decision tree lists all feasible solutions to the decision problem and various possible natural states, as well as the expected values ​​of each feasible method under various different states, enabling clearer and more comprehensive thinking and judgment.

[0022] Furthermore, this invention uses the most suitable temperature determined through training as the intelligent temperature, which is more in line with the current state of the battery and helps to extend the battery's lifespan. Attached Figure Description

[0023] Figure 1 This is a schematic flowchart of an embodiment of the charging and heating method of the present invention;

[0024] Figure 2 A decision tree model diagram of an embodiment of the charging and heating method of the present invention;

[0025] Figure 3 A schematic flowchart illustrating an embodiment of the charging and heating process of the battery of the present invention when it is fully charged;

[0026] Figure 4 A schematic flowchart illustrating an embodiment of the present invention's battery charging and heat preservation after full charging;

[0027] Figure 5 A schematic diagram of a process for charging and heating an embodiment of the present invention when the battery is charged to half charge;

[0028] Figure 6This is a schematic flowchart illustrating an embodiment of an abnormal situation that occurs during battery charging according to the present invention.

[0029] Figure 7 A schematic diagram of a structure of an embodiment of the charging heating device provided by the present invention; Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0031] It should be understood that the illustrative drawings are not drawn to scale. The flowcharts used in this invention illustrate operations implemented according to some embodiments of the invention. It should be understood that the operations in the flowcharts may be implemented out of order, and steps without logical contextual relationships may be reversed or performed simultaneously. Furthermore, those skilled in the art, guided by the content of this invention, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor systems and / or microcontroller systems.

[0032] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0033] See Figure 1 This invention provides a charging heater and charging heating method for lithium batteries at low temperatures, the specific steps of which include:

[0034] S1, acquire the battery's temperature and current status information.

[0035] S2 uses temperature as the primary feature for differentiation and the current state information as the secondary feature for differentiation to generate a decision tree.

[0036] S3, through iterative optimization of the decision tree, obtains the judgment conditions for charging and heating and executes them;

[0037] S4. After the battery charging is completed, obtain the set heat preservation range after the battery is fully charged, and perform heat preservation on the battery within the set heat preservation range.

[0038] Further, in step S1, the state information also includes the SOC, SOH, charging method, usage scenario, etc. of the battery.

[0039] In some embodiments of the present invention, the usage scenario includes charging the battery to full charge or charging the battery to half charge. Correspondingly, the charging and heating process of the present invention includes charging and heating, charging heat preservation, shelving preset, abnormal handling, etc.

[0040] I. Charging and Heating

[0041] It can be understood that in the charging and heating of the present invention, temperature is used as one of the conditions for feature differentiation, and then the state information of the battery is introduced for differentiation, such as SOC, SOH, charging method (fast charging or slow charging), and usage scenario, etc. as secondary feature differentiation conditions, to generate a decision tree, as Figure 2 shown, and finally, the decision tree is iteratively optimized as the heating judgment condition, as shown in Table 1 below.

[0042] Table 1 Heating Judgment Conditions of the Present Invention

[0043] serial number Battery Health temperature Charging method Equilibrium method heating Charge 1 pneumatic healthy Too low temperature Fast charging initiative no no 2 Low power good low temperature slow charge passive yes yes 3 China Power Difference medium temperature Fast charging passive yes no 4 High electricity healthy normal temperature Fast charging passive no yes 5 Fully charged healthy overheat slow charge passive no no

[0044] The secondary feature differentiation conditions can be set according to the situation. In some possible implementation manners, empty battery SOC = 0; low battery SOC 0 - 20; medium battery SOC 20 - 80; high battery SOC 80 - 100; full battery SOC = 100;

[0045] Healthy SOH = 100; good SOH 80 - 100; poor SOH < 80;

[0046] Too low temperature T0 ≤ -20°C; low temperature -20°C < T0 < 6°C; medium temperature T0 ≥ 6°C; high temperature T0 ≥ 15°C; overheat T0 ≥ 50°C. <​​​​​​Furthermore, in some embodiments of the present invention, the charging heating is accomplished by a charging heater, the charging output and heating output of which are separate; the application scenario is when charging a battery to full capacity, setting temperature thresholds from low to high: T1 (e.g., -20°C), T2 (e.g., 6°C), T3 (e.g., 15°C), and T4 (e.g., 50°C), see [reference needed]. Figure 3 The conditions for determining the charging and heating are as follows:

[0050] S301. When the battery temperature is too low, neither charging nor heating shall be performed; preferably, too low temperature means battery temperature T0 ≤ -20℃.

[0051] S302. When the battery is in a low-temperature state, only the heating relay is closed for heating; preferably, the low-temperature state is -20℃. <T0<6℃;

[0052] S303: When the battery is in a medium-temperature state, the charging relay is closed to start charging while heating; preferably, the medium-temperature state is T0≥6℃;

[0053] S304. When the battery is in a high-temperature state, the heating relay is disconnected to stop heating and only charging is performed; preferably, the high-temperature state is T0≥15℃;

[0054] S305. When the battery overheats, the charging relay is disconnected and charging is stopped; preferably, the battery overheating is T0≥50℃.

[0055] S306. During the charging process, the judgment condition is selected and executed based on the real-time battery temperature; the charging relay is disconnected and charging is stopped after the battery pack is fully charged.

[0056] For example, if the battery temperature drops below 15°C but above 6°C during charging, repeat steps S303 and S304; or if the battery temperature drops below 6°C during charging, repeat steps S302 to S304.

[0057] II. Charging and heat preservation:

[0058] Using batteries in low-temperature environments can cause significant damage and greatly reduce their cycle life. If the vehicle needs to be used soon after being fully charged, heating it before discharging would delay usage and cause inconvenience. Therefore, the charging heater can be equipped with a battery heat preservation function and corresponding setting buttons. The battery heat preservation function of the charging heater can be set before charging, and when the battery pack is fully charged, charging will stop but the temperature will be maintained by the heating components.

[0059] Further, see Figure 4 Step S4 obtains the set heat preservation range after the battery is fully charged, and the specific steps of heat preservation of the battery within the set heat preservation range include:

[0060] S401. Obtain the set insulation range based on the insulation function settings;

[0061] S402, The actual temperature of the battery is maintained within the set insulation range through the heating circuit.

[0062] In some embodiments of the present invention, the heat preservation function is set in three ways: one-click, numerical input, and intelligent temperature. One-click is the system's default heat preservation range. Numerical input is a way for users to set the heat preservation range themselves, but the temperature range is also limited. Intelligent temperature is a temperature threshold value determined by the learning results of a decision tree.

[0063] When using the one-button setting method, the heat preservation function setting signal is transmitted to the BMS chip, which then controls the temperature. If the battery temperature is detected to be below 10°C, heating is initiated to raise the temperature to 15°C, and then the heating relay is disconnected to stop heating. This cycle is repeated to maintain the battery temperature.

[0064] When using a numerical input setting method, users can set the upper and lower limits of the heat preservation temperature via the input buttons on the charging heating device, such as an upper limit of 20℃ and a lower limit of 8℃. The BMS chip receives this value and then controls the heat preservation temperature within this range. However, there are limitations to the setting of the upper and lower temperature limits; for example, the upper limit cannot exceed 25℃, and the lower limit cannot be lower than 6℃.

[0065] Intelligent temperature detection determines the most suitable temperature through training. Decision trees deal with discrete data. When discrete data is mixed with continuous data, we want to discretize the continuous data. We can pre-divide the range of continuous values ​​into multiple intervals, treating each interval as an attribute value, thus discretizing the continuous data. Given a training set D and a continuous attribute temperature a, where a has n distinct values ​​in D, first sorted in ascending order, denoted as {a...} 1 ,a 2 ,…,a n Based on the partition point t, D can be divided into subsets Di. t - and D t + , where D t - It includes samples whose value for attribute a is not greater than t, D t + This includes samples whose attribute a value is greater than t. Clearly, for adjacent attribute values ​​a and a+1, any value of t within the interval [a, a+1) produces the same partitioning result. Therefore, for continuous attribute a... i+1 We can examine the set of candidate partition points containing n-1 elements:

[0066]

[0067] That is, the interval [a i a i+1 The median of ) These can be considered as candidate split points, and then, like discrete attribute values, these split points can be selected to partition the sample set using the following formula:

[0068]

[0069] Where Gain(D, a, t) is the information gain of the sample set D after bisecting based on the partition point t. During partitioning, the partition point that maximizes Gain(D, a, t) is selected as the critical temperature condition, thus obtaining the optimal partition point; the two optimal partition points determined by adjacent intervals are selected as the upper and lower limits of the new temperature range, that is, the intelligent temperature range is obtained, and then heat preservation measures are implemented.

[0070] This invention uses training to determine the most suitable temperature as the intelligent temperature, which is more in line with the current state of the battery and helps to extend the battery's lifespan.

[0071] III. Set aside the pre-set plan

[0072] Furthermore, if the vehicle is not used immediately after charging, due to the characteristics of lithium batteries, they are generally charged to half-charge and then stored to ensure battery life and safety. The charging heater's preset storage function allows you to set the desired charging level before charging, i.e., the usage scenario is charging the battery to half-charge. See [link to relevant documentation]. Figure 5 The specific conditions for determining the charging and heating are as follows:

[0073] S311. By comparing the battery's SOC value with a preset value, the battery charging and heating process is directly terminated when the SOC value is ≥ the preset value.

[0074] S312. When the SOC value is less than the preset value, start the charging and heating process until the battery is charged to the preset capacity, then end the charging and heating process. In the specific charging and heating process, it is only necessary to ensure that the charging capacity reaches the preset capacity value; other processes can be the same as steps S301 to S306.

[0075] IV. Abnormal Handling

[0076] The BMS chip is connected to an exception handling module to handle abnormal situations during the charging and heating process; see also Figure 6 The specific processing steps include:

[0077] S501: If the battery temperature drops below a preset value during charging and remains unchanged for a period of time, heating will stop and a heating circuit fault warning message will be issued.

[0078] For example, if the battery temperature drops below -15℃ during charging and remains unchanged for 1 hour, heating will stop and the BMS chip will issue a heating circuit fault warning message; or the heating component is configured to heat from -20℃ to 6℃ in 2 hours. If the battery temperature cannot be heated to above 6℃ within 3 hours, charging and heating will end and the BMS chip will issue a heating circuit fault warning message.

[0079] S502. If the highest single-cell voltage or the highest single-cell temperature exceeds the threshold, an overcharge alarm signal or an overtemperature alarm signal will be issued; then the output current will be cut off, the output current will be detected and fed back, and if there is still current output, an abnormality prompt will be issued.

[0080] If the charging relay becomes stuck, the battery will continuously charge. If the highest single-cell voltage exceeds a certain limit (e.g., 4.2V for a ternary lithium battery), the BMS chip will send an overcharge alarm signal, and the charging circuit will automatically cut off the output, detecting and feeding back the output current. If there is still current output at this time, the BMS chip will send an alarm signal to the cloud platform for abnormality notification.

[0081] If the heating relay becomes stuck, the battery will continuously heat up. If the highest single-cell temperature exceeds a certain limit (e.g., 50°C), the BMS chip will send an over-temperature alarm signal, and the heating circuit will automatically cut off the output, detecting and feeding back the output current. If there is still current output at this time, the BMS chip will send an alarm signal to the cloud platform for abnormality notification.

[0082] See Figure 7 The hardware system for implementing the charging and heating method of the present invention includes a charging and heating device comprising a data acquisition module S601, a BMS chip S602, a heating relay S603, a heating module S604, a charging relay S605, a charging module S606, and a power input module S607. The data acquisition module S601 is electrically connected to the BMS chip S602. The BMS chip S602 is electrically connected to the heating module S604 and the charging module S606, respectively. A heating relay S603 is provided between the BMS chip S602 and the heating module S604, and a charging relay S605 is provided between the BMS chip S602 and the charging module S606. The heating module S604 and the charging module S606 are electrically connected to a battery.

[0083] The data acquisition module S601 is used to collect relevant characteristic differentiation conditions of the battery S608, such as the temperature, charge, health status, and charging method of the battery S608. Specifically, taking temperature as an example, it can monitor the real-time temperature of the battery S608 through several temperature probes and transmit the temperature data to the BMS chip S602 in real time.

[0084] The power input module S607 is used to supply power to the BMS chip S602, the heating module S604 and the charging module S606.

[0085] Understandably, the power input module S607, the charging module S606, and the battery S608 form a charging circuit for charging the battery S608; the charging relay S605 controls whether the charging circuit is energized, so its position can be adjusted according to the actual situation, such as being placed between the charging module S606 and the battery or between the power input module S607 and the charging module S606; the position of the heating relay S603 is also adjustable.

[0086] The BMS chip S602 is used to receive relevant feature differentiation conditions, obtain the judgment conditions for charging and heating based on the relevant feature differentiation conditions, and issue instructions. By controlling the opening and closing states of the heating relay S603 and the charging relay S605, the heating and charging states of the battery are realized.

[0087] Preferably, the BMS chip S602 of the present invention is also electrically connected to a one-key setting module, a numerical setting module, and a status display module; wherein, the one-key setting module is used to select the system's default heat preservation range in heat preservation mode; the numerical setting module is used for users to set the heat preservation range themselves; and the status display module is used to display the status information of battery charging and heating.

[0088] Preferably, the S602 electrical connection abnormality handling module of the BMS chip of the present invention is used to handle abnormal situations during the charging and heating process.

[0089] Understandably, during the heat preservation process, the power input module S607 maintains continuous communication with the BMS chip S602, outputting current according to the current requested by the BMS chip S602. When the temperature is relatively low, such as below 10℃, the BMS chip S602 requests a larger heating current; when the temperature is relatively high, such as above 15℃, the BMS chip S602 requests a smaller heating current; when the set heat preservation range is relatively wide, the BMS chip S602 requests a larger heating current; when the set heat preservation range is relatively narrow, the BMS chip S602 requests a smaller heating current.

[0090] In some embodiments, the preset value in the preset function can be a value pre-set and stored in the BMS chip, or it can be a value set by the user. For example, the desired charging level can be set on the numerical setting module, and then a communication connection can be established with the BMS chip. The numerical setting module transmits the parameter to the BMS chip. If the SOC value estimated by the BMS chip is greater than or equal to the preset value, the charging connection fails, and the charging and heating device of the present invention is powered down. If the SOC value estimated by the BMS chip is less than the preset value, the charging and heating process is started. When the battery is charged to the preset level, the charging circuit and the heating circuit no longer output charging current and heating current, and notify the BMS chip to cut off the charging relay and the heating relay, and then the charging and heating device is powered down.

[0091] Preferably, in this invention, the charging heating device can be assembled with the battery to form a battery pack.

[0092] This invention improves the charging, heating, and heat preservation process of lithium battery packs at low temperatures by combining system, method, and algorithm aspects. It enables rapid and safe low-temperature heating and charging of battery packs, saves energy through improvements to the charging heater, and is also convenient for users.

[0093] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for charging and heating a lithium battery at low temperatures, characterized in that, It includes the following steps: Obtain the temperature and status information of the battery; Take the temperature as the main feature discrimination condition and the status information as the secondary feature discrimination condition to generate a decision tree; Through iterative optimization of the decision tree, obtain the judgment conditions for charging and heating and execute them; After the battery charging is completed, obtain the set heat preservation range after the battery is fully charged, and perform heat preservation on the battery within the set heat preservation range; The steps of obtaining the set heat preservation range after the battery is fully charged and performing heat preservation on the battery within the set heat preservation range specifically include: When the battery pack is fully charged, disconnect the charging circuit; Obtain the set heat preservation range according to the setting of the heat preservation function, and maintain the actual temperature of the battery within the set heat preservation range through the heating circuit; The settings of the heat preservation function are divided into a system default one-key setting, a user self-set numerical input type, and an intelligent temperature setting; The intelligent temperature setting is obtained by training temperature data, and the specific steps include: Given a training set D and a continuous attribute temperature a, where a has n distinct values ​​in D, first sort them in ascending order, denoted as {a}. 1 ,a 2 ,…,a n Discretize the continuous temperature data by dividing it into points t, resulting in a set of n-1 candidate dividing points. T ; Information gain after bisection based on the partition point t using the training set D. To obtain the optimal split point Two optimal dividing points determined by adjacent intervals are selected as the two critical values ​​at the ends of the intelligent temperature range.

2. The method for charging and heating a lithium battery at low temperatures according to claim 1, characterized in that, The status information also includes the SOC, SOH, charging method, and usage scenario of the battery.

3. The method for charging and heating a lithium battery at low temperatures according to claim 2, characterized in that, When the usage scenario is to charge the battery to full charge, set temperature thresholds T1, T2, T3, and T4 from low to high, and the judgment conditions for charging and heating are: When the battery temperature T0 ≤ T1, do not charge and do not heat; When T1 < T0 < T2, only heat; When T2 ≤ T0 < T3, heat and charge simultaneously; When T3 ≤ T0 < T4, stop heating and only charge; When T0 ≥ T4, stop charging.

4. The method for charging and heating a lithium battery at low temperatures according to claim 2, characterized in that, When the usage scenario is to charge the battery to half charge, the judgment conditions for charging and heating are: By comparing the SOC value of the battery with a preset value, when the SOC value ≥ the preset value, directly end the battery charging and heating process; When the SOC value < the preset value, start the charging and heating process, and end the charging and heating process until the battery is charged to the preset power.

5. A charging and heating device for lithium batteries at low temperatures, characterized in that, It includes a data acquisition module, a BMS chip, a heating relay, a heating module, a charging relay, a charging module, and a power input module; among them, The data acquisition module is electrically connected to the BMS chip and is used to collect the relevant feature discrimination conditions of the battery; The power input module, the heating relay, the heating module, and the battery are connected to form a heating circuit; the power input module, the charging relay, the charging module, and the battery are connected to form a charging circuit; the heating circuit and the charging circuit are respectively used to heat and charge the battery; the power input module is also connected to the BMS chip for power supply; The BMS chip is used to receive the relevant feature discrimination conditions, obtain the judgment conditions for charging and heating according to the relevant feature discrimination conditions, and issue instructions to control the opening and closing states of the charging relay and the heating relay; The charging and heating device is used in the charging and heating method according to any one of claims 1-4.

6. The lithium battery charging and heating device at low temperatures according to claim 5, characterized in that, It further includes a one-key setting module, a numerical setting module, and a status display module that are electrically connected to the BMS chip; Among them, the one-key setting module is used to select the system default heat preservation range in the heat preservation mode; the numerical setting module is used for the user to set the heat preservation range by himself; the status display module is used to display the status information of the battery charging and heating.

7. The lithium battery charging and heating device at low temperatures according to claim 5, characterized in that, The BMS chip is electrically connected to an abnormal handling module, which is used to handle abnormal situations during the charging and heating process.

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