A vehicle battery charging control method and battery management system

Abstract

The present invention relates to a vehicle battery charging control method and a battery management system, comprising the following steps: controlling a hot air blower to heat the battery; determining a low temperature area of ​​the battery; and controlling the battery management system to increase the charging current of at least one battery cell in the low temperature area. The hot air blower is controlled to heat the battery. During the process of the hot air blower heating the battery, some positions of the battery cannot be heated well, thereby forming a low temperature area. The low temperature area of ​​the battery is determined, and the charging current of at least one battery cell in the low temperature area is controlled to be increased, thereby increasing the temperature of the battery cell in the low temperature area. In this way, the battery cell that is not fully heated by the hot air blower can be heated. Through the cooperation of the hot air blower and the self-heating of the battery cell, each battery cell inside the battery can be evenly heated, so that the battery can reach and maintain a normal charging temperature faster, thereby improving the charging efficiency of the battery in a low temperature environment.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicles, and in particular to a vehicle battery charging control method and a battery management system. Background Art

[0002] The charging efficiency of the battery of an electric vehicle is greatly affected by temperature. In cold areas, the low temperature environment causes the charging efficiency of the battery to slow down. Therefore, some cars are equipped with a hot air blower. When the battery is charged, the hot air is blown to the battery by the hot air blower to heat the battery and keep the battery at a suitable charging temperature. However, the hot air blower can only heat one side of the battery surface, so that the battery cell on the heated side can be well heated. Due to the current extreme pursuit of volume utilization, there is a lack of sufficient heat transfer channels in the battery shell. Therefore, the battery cells close to the middle of the battery shell or far away from the blower are difficult to heat, resulting in uneven temperatures of each battery cell, which makes it impossible to charge the battery well. The air heat transfer efficiency can be improved by increasing the gap between the battery cells, but this will affect the volume utilization of the battery; if liquid is used as a heat transfer medium to improve the heat transfer efficiency, additional costs will be added and there may be a risk of leakage.

[0003] Currently, there is a method of heating the battery cell by self-heating. However, when the battery cell is below 0°C, it is difficult to heat the battery cell by self-heating. The heating efficiency is slow and serious lithium deposition will occur, affecting the battery life. Summary of the invention

[0004] Based on this, it is necessary to provide a vehicle battery charging control method and a battery management system.

[0005] A vehicle battery charging control method comprises the following steps:

[0006] The hot air blower is controlled to heat the battery; wherein the hot air blower includes a heating component and an air supply component. After the heating component is heated up, it heats the surrounding ambient gas, and the air supply component delivers the ambient gas to the surface of the battery, thereby heating the battery.

[0007] Determine the low temperature area of ​​the battery; specifically, receive temperature information of each area of ​​the battery to determine the low temperature area of ​​the battery. More specifically, receive temperature information fed back by temperature sensors of each area of ​​the battery to determine the low temperature area of ​​the battery. Specifically, the low temperature area includes at least one battery cell. For example, the low temperature area includes a battery cell, and when the temperature of any battery cell inside the battery is lower than a preset temperature, it is determined that the area where the battery cell is located is a low temperature area.

[0008] In one embodiment, the temperature of the low temperature area is less than the preset temperature, specifically, the temperature of the low temperature area is less than 20°C. In this embodiment, the low temperature area is the average temperature of multiple battery cells. The charging efficiency of battery cells below 20°C is slow, and they need to be further heated by self-heating. In other embodiments, the low temperature area is the ambient temperature around multiple battery cells. At this ambient temperature, the battery cells are prone to low temperatures. It should be understood that in this application, if the number of battery cells in each area is greater than two, the low temperature area is detected instead of just the temperature of the battery cells. For example, when a certain area is higher than 20°C, even if there are relatively low temperature battery cells in the area, the temperature of the adjacent battery cells is higher. At this time, there is no need to self-heat the low temperature battery cells, because increasing the charging current of the low temperature battery cells has the risk of lithium precipitation. As long as the area is not a low temperature area, the battery cells are not self-heated, but the heat of the area is balanced by naturally transferring heat between adjacent battery cells. In order to better balance the temperature of each battery cell and avoid the problem of lithium precipitation, preferably, the low temperature area includes at least two battery cells, and the temperature information of multiple battery cells is integrated to determine whether to heat the battery cells in the low temperature area.

[0009] In one embodiment, the low temperature area includes 1 to 4 battery cells. For example, the low temperature area includes two battery cells, and when it is determined that the average temperature of the area composed of every two adjacent battery cells is lower than the average temperature or preset temperature of the remaining areas, the area composed of the two battery cells is determined to be a low temperature area. For another example, the low temperature area includes three battery cells, and when it is determined that the average temperature of the area composed of every three adjacent battery cells is lower than the average temperature or preset temperature of the remaining areas, the area composed of the three battery cells is determined to be a low temperature area. For another example, the low temperature area includes three battery cells, and when it is determined that the average temperature of the area composed of every three adjacent battery cells is lower than the average temperature or preset temperature of the remaining areas, the area composed of the four battery cells is determined to be a low temperature area, and the four battery cells are arranged in a rectangular shape, in which two battery cells are arranged adjacent to each other. For another example, the low temperature area includes n battery cells, and when it is determined that the average temperature of the area composed of every n adjacent battery cells is lower than the average temperature or preset temperature of the remaining areas, the area composed of the n battery cells is determined to be a low temperature area, where n is a natural number greater than 0.

[0010] Control to increase the charging current of at least one battery cell in the low temperature region. Specifically, during normal charging, the battery cells of the battery are charged with a preset charging current. After the low temperature region of the battery is determined, control to increase the charging current of at least one battery cell in the low temperature region. When the charging current of at least one battery cell is increased, the battery cell is heated up, which is conducive to the temperature rise of the battery cell, and further transfers heat to adjacent battery cells to heat the overcooled battery cells.

[0011] The above-mentioned vehicle battery charging control method controls the hot air blower to heat the battery. During the process of the hot air blower heating the battery, some positions of the battery cannot be heated well, thereby forming a low-temperature area. The low-temperature area of ​​the battery is determined, and the charging current of at least one battery cell in the low-temperature area is controlled to increase, thereby increasing the temperature of the battery cell in the low-temperature area. In this way, the battery cell that is not fully heated by the hot air blower can be heated. Through the coordination of hot air blower heating and battery cell self-heating, each battery cell inside the battery can be evenly heated, so that the battery can reach and maintain a normal charging temperature faster, thereby improving the charging efficiency and charging rate of the battery in a low-temperature environment.

[0012] In one of the embodiments, in the step of controlling the increase of the charging current of at least one battery cell in the low temperature region, the temperature of each battery cell in the low temperature region is determined, and the charging current of the battery cell whose temperature is within the preset temperature range is controlled to be increased. When the temperature of the battery cell is too low, a larger charging current is likely to cause lithium precipitation, and when the temperature of the battery cell is high, continuing to increase the charging current will further cause heating, which is likely to cause thermal runaway. In this embodiment, the temperature of the battery cell in the preset temperature range is increased, so that the battery cell in the low temperature region can be quickly heated, and the rapidly heated battery cell can also transfer heat to the adjacent battery cell, so that each battery cell in the low temperature region can be quickly heated, thereby uniformly heating the battery as a whole. In one of the embodiments, the preset temperature range is 0℃~30℃, within which range, the battery cell can be well heated by controlling the increase of the charging current, and the charging current of the battery cell at 0℃ can be avoided, thereby avoiding the phenomenon of lithium precipitation in the electrode of the battery cell. For example, a certain area includes a first battery cell and a second battery cell, wherein the temperature of the first battery cell is 10°C, and the temperature of the second battery cell is -2°C, wherein the combined average temperature of the two is 4°C. It can be seen that the area where the first battery cell and the second battery cell are located is less than 20°C, and is determined to be a low temperature area, and the charging current of the first battery cell is increased instead of the charging current of the second battery cell. This is because the temperature of the second battery cell is lower than 0°C, and lithium deposition is likely to occur after increasing the charging current. Therefore, the self-heating function of the first battery cell is controlled to be enabled, and then the heat is transferred to the second battery cell. When the second battery cell reaches above 0°C, it is determined whether to enable the self-heating of the second battery cell based on the temperature of the low temperature area. For another example, a certain area includes a third battery cell and a fourth battery cell, wherein the temperature of the third battery cell is 10°C, and the temperature of the fourth battery cell is 6°C, wherein the average temperature of the two is 8°C. It can be seen that the area where the third battery cell and the fourth battery cell are located is less than 20°C, and is determined to be a low temperature area, then the charging current of the third battery cell and the fourth battery cell is increased at the same time. This is because the temperature of the third battery cell and the fourth battery cell is between 0 and 30°C, and after increasing the charging current, the problem of lithium plating can be avoided as much as possible, so that the third battery cell and the fourth battery cell can reach the appropriate charging temperature more quickly. For another example, a certain area includes the fifth battery cell and the sixth battery cell, where the temperature of the fifth battery cell is 30°C, and the temperature of the sixth battery cell is 18°C, where the average temperature of the two, that is, the temperature of the low temperature area, is 24°C. It can be seen that the area where the fifth battery cell and the sixth battery cell are located is greater than 20°C, and it is definitely not a low temperature area. Although the temperature of the sixth battery cell is between 0 and 30°C, since this area does not belong to the low temperature area, there is no need to increase the charging current of the sixth battery cell, and it is sufficient to transfer heat from the fifth battery cell to the sixth battery cell naturally, which can avoid the lithium deposition problem that may occur in the sixth battery cell. In this way, the above-mentioned charging control method can make the low temperature area reach above the preset temperature as soon as possible, and avoid the problem of lithium deposition in the battery cell electrode as much as possible.

[0013] In one embodiment, in the step of controlling to increase the charging current of at least one battery cell in the low temperature region, the temperature rise rate of each battery cell in the low temperature region is determined, and when the temperature rise rate of the battery cell is lower than the temperature rise threshold, the charging current of the adjacent battery cell is controlled to be increased. For example, after increasing the charging current of the seventh battery cell, if the temperature rise rate is lower than the temperature rise threshold, it means that the low temperature has affected the charging of the seventh battery cell, and continuing to charge with the increased charging current may cause lithium deposition problems inside the seventh battery cell. Therefore, the charging current of the adjacent eighth battery cell is controlled to be increased so that the eighth battery cell is heated up. After the eighth battery cell is heated up, it can transfer heat to the seventh battery cell, so that the temperature rise rate of the seventh battery cell is faster, so that the seventh battery cell enters the normal charging temperature faster. Further, when the temperature rise rate of the battery cell is lower than the temperature rise threshold, the charging current of the battery cell is controlled to drop to a preset charging current, and the charging current of the adjacent battery cell is controlled to be increased. It is worth mentioning that this method of controlling the charging current of adjacent battery cells can also be used across regions, that is, increasing the charging current of battery cells in areas adjacent to low-temperature areas, thereby transferring heat to each battery cell in the low-temperature area.

[0014] In one of the embodiments, the hot air blower is controlled to heat the low-temperature area. In this way, the temperature of the low-temperature area can be raised more directly, and combined with controlling the charging current, the battery can be better heated evenly.

[0015] A battery management system, comprising:

[0016] A control module, used for controlling a hot air blower to heat the battery;

[0017] A determination module, used to determine a low temperature area of ​​the battery;

[0018] The regulating module is used to control and increase the charging current of at least one battery cell in the low temperature area.

[0019] The above-mentioned battery management system can control the hot air blower to heat the battery so as to heat the battery. During the process of the hot air blower heating the battery, some positions of the battery cannot be heated well, thereby forming a low-temperature area. The low-temperature area of ​​the battery is determined, and the charging current of at least one battery cell in the low-temperature area is controlled to increase, thereby increasing the temperature of the battery cell in the low-temperature area. In this way, the battery cell that is not fully heated by the hot air blower can be heated. Through the cooperation of the hot air blower and the self-heating of the battery cell, each battery cell inside the battery can be evenly heated, so that the battery can reach and maintain the normal charging temperature faster, thereby improving the charging efficiency of the battery in a low-temperature environment.

[0020] A computer device comprising: a memory and a processor;

[0021] The memory is used to store computer programs;

[0022] The processor is used to implement the steps of the vehicle battery charging control method in any of the above embodiments when executing the program stored in the memory.

[0023] A computer-readable storage medium stores a computer program, and when the program is executed by a processor, the steps in the vehicle battery charging control method described in any of the above embodiments are implemented. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The figure is a flow chart of a vehicle battery charging control method according to an embodiment.

[0025] Figure 2 The figure is a schematic diagram of the principle of a vehicle battery charging control method according to an embodiment. DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0027] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. In the description of the present application, the meaning of "several" is at least one, such as one, two, etc., unless otherwise clearly and specifically defined.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0029] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0030] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0031] like Figure 1 and Figure 2 As shown, in one embodiment, a vehicle battery charging control method is provided, comprising the following steps:

[0032] S1, controls the hot air blower to heat the battery. Figure 2 It can be seen that the hot air blower heats the battery 200 by blowing hot air onto the surface of the battery 200 . A plurality of battery cells are arranged in an array inside the battery 200 , one of which is the battery cell 400 .

[0033] S2, determining the low temperature area of ​​the battery. Figure 2 It can be seen that the four battery cells far away from the hot air blower 100 constitute a low temperature area 300 because they are not heated by the hot air blower 100 .

[0034] S3, controlling to increase the charging current of at least one battery cell in the low temperature region. Figure 2 It can be seen that the present embodiment heats one of the four battery cells, and the battery cell 400 is provided with a battery shell. Since the battery shell is more easily in contact with the hot air of the hot air blower, the battery cell 400 at this time has a relatively high temperature among the four battery cells in the low-temperature area 300, and can reach the preset temperature range earlier, thereby controlling the battery cell 400 to increase the charging current to achieve self-heating more smoothly. After the battery cell is self-heated, the heat will be transferred to the other three adjacent battery cells in the low-temperature area.

[0035] The above-mentioned vehicle battery charging control method controls the hot air blower to heat the battery. During the process of the hot air blower heating the battery, some positions of the battery cannot be heated well, thereby forming a low-temperature area. The low-temperature area of ​​the battery is determined, and the charging current of at least one battery cell in the low-temperature area is controlled to increase, thereby increasing the temperature of the battery cell in the low-temperature area. In this way, the battery cell that is not fully heated by the hot air blower can be heated. Through the coordination of hot air blower heating and battery cell self-heating, each battery cell inside the battery can be evenly heated, so that the battery can reach and maintain a normal charging temperature faster, thereby improving the charging efficiency and charging rate of the battery in a low-temperature environment.

[0036] The following is a specific embodiment.

[0037] Example 1: The battery includes 4416 21700 cylindrical cells, and the battery capacity is about 75 kWh. The battery is placed in a refrigerator at -10°C for charging test, during which the battery capacity is charged from 30 kWh to 60 kWh, and the charger uses Tesla's third-generation wall-mounted charging connector.

[0038] The following vehicle battery charging control method is adopted, comprising the following steps:

[0039] Receive a charging instruction from the user and control the battery to be charged with a preset charging current of 12A.

[0040] The hot air blower is controlled to heat the battery, wherein the rated air supply volume of the hot air blower is 250 CFM and the rated heating power is 3 kW.

[0041] Receive information fed back by the temperature sensor inside the battery, and determine the low temperature area of ​​the battery, wherein each low temperature area is defined to include 3 battery cells during confirmation. The low temperature area detects the ambient temperature of the 3 battery cells. The temperature of the low temperature area is less than 20°C.

[0042] Determine the temperature of each battery cell in the low temperature area, control and increase the charging current of the battery cells with a temperature of 0°C to 30°C in the low temperature area to 16A, and continue charging until the battery cells reach 30°C and drop to 12A. The vehicle battery charging control method of this embodiment is used to cooperate with the charging pile, and allocate the charging current for each battery cell in the battery through the battery management system. When the low temperature area is confirmed, the charging current of the battery cells with a temperature of 0°C to 30°C in the low temperature area is increased. The battery cells in this temperature range can be better heated up to avoid the problem of lithium precipitation caused by low temperature overcharging or thermal runaway caused by high temperature. After the battery cells in this temperature range are heated up, they can transfer heat to the remaining adjacent battery cells with too low temperature.

[0043] The temperature rise rate of each battery cell in the low temperature area is determined, and when the temperature rise rate of the battery cell is lower than the temperature rise threshold, the charging current of the adjacent battery cell is controlled to increase. In this way, the battery cell with a higher temperature rise rate can be heated up, thereby transferring heat to the battery cell with a slower temperature rise rate, thereby allowing the battery cell with a slower temperature rise rate to heat up faster.

[0044] Comparative Example 1: The battery includes 4416 21700 cylindrical cells, and the battery capacity is about 75kWh. The battery is placed in a refrigerator at -10°C for charging test, and the battery capacity is charged from 30kWh to 60kWh during charging.

[0045] Comparative Example 2: The battery includes 4416 21700 cylindrical cells with a battery capacity of about 75kWh. The battery is placed in a refrigerator at -10°C for charging test, and the battery capacity is charged from 30kWh to 60kWh during charging. During the charging process, the hot air blower is controlled to heat the battery. The rated air supply volume of the hot air blower is 250CFM and the rated heating power is 3kW.

[0046] The time for the battery cells of the above-mentioned embodiments and comparative examples to be heated from -10°C to 30°C and the time for the battery to be charged from 30kWh to 60kWh were detected. The batteries of the above-mentioned embodiments and comparative examples were charged to 410V at a rate of 0.5 at -10°C, and discharged to 310V at a rate of 1C, and the above was one cycle. After 1500 charge and discharge cycles, the battery was disassembled, and the battery cells in the 5 central areas were taken out to observe the lithium deposition on the surface of the electrode of the battery cell. The degree of lithium deposition was determined as follows: It was determined according to the state of the electrode surface when fully charged. When the surface of the electrode was golden yellow and the area of ​​gray displayed was less than 0.5%, it was determined that the electrode did not deposit lithium. When most of the electrode was yellow, but gray was observed in some positions, and the gray area was greater than 0.5%, it was determined that the electrode deposited lithium.

[0047]

[0048] From the data in the above table, it can be seen that the time for Example 1 to heat up from -10°C to 30°C is the shortest, and the overall charging time is shorter. This is because the battery cell is heated from the outside by a hot air blower, and the battery cell is heated from the inside by adjusting the charging current. The two heating methods cooperate with each other, which can better maintain each battery cell at 30°C, so that the battery can be better maintained at a state with high charging efficiency for charging. The battery cell of Comparative Example 1 takes a long time to reach 30°C, and at the same time, in order to maintain the temperature of each battery cell, the charging efficiency is significantly reduced, so the charging time is the longest. In Comparative Example 2, although a hot air blower is used, the time for the battery cell to reach 30°C as a whole is also long. At the same time, since the battery is heated by a hot air blower alone, each battery cell cannot maintain a uniform temperature, which affects the charging efficiency of the battery cell, and the charging time is often longer than that of Example 1. In summary, since Example 1 adopts the combination of hot air blower heating and battery cell self-heating, the charging time is shortened and the charging efficiency is improved.

[0049] From the results of disassembling the battery after multiple cycles, it can be seen that the pole pieces of the battery cells of Comparative Examples 1 and 2 have both experienced lithium deposition. The reason for lithium deposition in Comparative Example 1 is that the battery cells are charged at too low a temperature, and the temperature rises slowly during charging. In Comparative Example 2, the temperature is uneven at the beginning of charging, and the duration of the uneven temperature is significantly longer than that of Example 1. Therefore, the battery cells with lower initial temperatures are also prone to lithium deposition during the charging process. After the battery cells of Example 1 were disassembled, no lithium deposition occurred on the pole pieces. This is because Example 1 uses a combination of hot air blower heating and battery cell self-heating to quickly and evenly heat each battery cell of the battery, and further only increases the charging current of the battery cells at 0°C to 30°C, and does not enable the self-heating function for the battery cells with lower temperatures, thereby avoiding lithium deposition on the pole pieces.

[0050] It is worth mentioning that in the present application, the battery may also be referred to as a battery pack, and the battery cell may also be referred to as a battery monomer.

[0051] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0052] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A vehicle battery charging control method, characterized in that: The steps include: Control the hot air blower to heat the battery; determining a low temperature region of the battery; Control to increase the charging current of at least one battery cell in the low temperature area; in the step of controlling to increase the charging current of at least one battery cell in the low temperature area, determine the temperature of each battery cell in the low temperature area, and control to increase the charging current of the battery cells whose temperature is within a preset temperature range; the preset temperature range is 0°C to 30°C, wherein the heating rate of each battery cell in the low temperature area is determined, and when the heating rate of the battery cell is lower than the heating threshold, control the charging current of the battery cell to drop to a preset charging current, and control to increase the charging current of the adjacent battery cells.

2. The vehicle battery charging control method according to claim 1, characterized in that: The hot air blower is controlled to heat the low temperature area.

3. The vehicle battery charging control method according to claim 1, characterized in that: The step of controlling the hot air blower to heat the battery includes: receiving a charging instruction from a user.

4. The vehicle battery charging control method according to claim 3, characterized in that: After the step of receiving the charging instruction from the user, the method further includes: controlling the battery to be charged with a preset charging current.

5. The vehicle battery charging control method according to claim 1, characterized in that: The low temperature area includes 1 to 4 battery cells.

6. The vehicle battery charging control method according to claim 1, characterized in that: The temperature of the low temperature area is less than 20°C.

7. A battery management system, characterized in that: include: A control module, used for controlling a hot air blower to heat the battery; A determination module, used to determine a low temperature area of ​​the battery; A regulating module is used to control and increase the charging current of at least one battery cell in the low-temperature area. In the step of controlling and increasing the charging current of at least one battery cell in the low-temperature area, the temperature of each battery cell in the low-temperature area is determined, and the charging current of the battery cells whose temperature is within a preset temperature range is controlled to be increased; the preset temperature range is 0°C to 30°C, wherein the heating rate of each battery cell in the low-temperature area is determined, and when the heating rate of the battery cell is lower than the heating threshold, the charging current of the battery cell is controlled to drop to a preset charging current, and the charging current of the adjacent battery cells is controlled to be increased.

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