Battery temperature control method, battery temperature control system, battery management system and vehicle

Abstract

This invention provides a battery temperature control method, a battery temperature control system, a battery management system, and a vehicle, belonging to the field of battery temperature control. The battery temperature control method includes: determining a first time required for the battery to reach a current-limiting temperature from the initial temperature when charging the battery and a preset activation temperature of the temperature control system, wherein the initial temperature is the battery temperature when charging begins, and the preset activation temperature is greater than the initial temperature and less than the current-limiting temperature; and determining the activation temperature and activation time of the temperature control system based on the first time and the current-limiting charging time of the battery. This method helps to achieve efficient battery charging and avoid unnecessary power consumption by the battery cooling system.

Description

Technical Field

[0001] This invention relates to the field of battery temperature control, and more specifically to a battery temperature control method, a battery temperature control system, a battery management system, and a vehicle. Background Technology

[0002] As the demand in the new energy vehicle market increases, battery temperature control, a crucial component of battery management, faces increasingly severe challenges. Power batteries require high-power charging capabilities to meet user convenience needs, which necessitates applying high voltage or current during charging. While developing higher-power charging methods, the issue of battery overheating during high-power charging has become increasingly apparent. High current generates significant resistive heat in the vehicle's battery. Consequently, as the battery temperature rises, the permissible charging current must decrease accordingly. Therefore, incorporating a battery cooling system during charging, activating it when necessary, effectively lowers the battery temperature.

[0003] However, existing battery cooling systems typically set the trigger temperature for cooling on and off to a fixed value, without matching the battery's charging performance curve, resulting in limitations on battery performance or wasted cooling energy. Summary of the Invention

[0004] The purpose of this invention is to provide a battery temperature control method, a battery temperature control system, a battery management system, and a vehicle. This method helps to achieve efficient battery charging and avoid unnecessary power consumption in the battery cooling system. Through this invention, the estimated cooling / heating time can be calculated, and the trigger temperature (i.e., the start-up temperature) for the temperature control system to operate can be controlled, thereby maximizing power savings in the temperature control system while ensuring battery performance.

[0005] To achieve the above objectives, embodiments of the present invention provide a battery temperature control method. The method includes: determining a first time required for the battery to reach a current-limiting temperature from the initial temperature based on the initial temperature of the battery during charging and a preset activation temperature of the temperature control system, wherein the initial temperature is the battery temperature when the battery begins charging, and the preset activation temperature is greater than the initial temperature and less than the current-limiting temperature; and determining the activation temperature and activation time of the temperature control system based on the first time and the current-limiting charging time of the battery.

[0006] Optionally, before determining the first time required for the battery to reach the current-limiting temperature from the initial temperature based on the initial temperature of charging the battery and the preset activation temperature of the temperature control system, the battery temperature control method further includes: when charging the battery and the temperature control system is not activated, determining a second time required for the battery to reach the current-limiting temperature from the initial temperature; if the second time is greater than or equal to the current-limiting charging time of the battery, then the temperature control system is not activated; if the second time is less than the current-limiting charging time of the battery, then the temperature control system is activated.

[0007] Optionally, the second time is determined by the following method: determining the heat generation power of the battery during charging based on the equivalent internal resistance and charging current of each cell in the battery; and determining the second time based on the heat generation power, the initial temperature, the current limiting temperature, the specific heat capacity of the battery, and the battery mass.

[0008] Optionally, the second time is determined by the following formula:

[0009]

[0010] P charge =I c1 2 r 等效 n,

[0011] Where t2 is the second time, ΔT1 is the temperature difference between the initial temperature and the current-limiting temperature, C is the specific heat capacity of the battery, m is the mass of the battery, and P charge The heating power; I c1 For the charging current, r 等效 The equivalent internal resistance is n, and the number of cells in the battery is n.

[0012] Optionally, the first time is determined by the following method: determining the heat generation power of the battery during charging based on the equivalent internal resistance and charging current of each cell in the battery; determining the third time required for the battery to reach the preset start-up temperature from the initial temperature based on the heat generation power, the specific heat capacity of the battery, and the battery mass; determining the fourth time required for the battery to reach the current limiting temperature from the preset start-up temperature based on the heat generation power, the cooling power of the temperature control system, the specific heat capacity of the battery, and the battery mass; and determining the sum of the third time and the fourth time as the first time.

[0013] Optionally, the first time is determined by the following formula:

[0014]

[0015] Pcharge =I c1 2 r 等效 n,

[0016] Where t1 is the first time, ΔT2 is the temperature difference between the initial temperature and the preset start-up temperature, ΔT3 is the temperature difference between the preset start-up temperature and the current-limiting temperature, C is the specific heat capacity of the battery, m is the mass of the battery, and P charge P is the heating power. ac The cooling power; I c1 For the charging current, r 等效 The equivalent internal resistance is n, and the number of cells in the battery is n.

[0017] Optionally, determining the start-up temperature and start-up time of the temperature control system based on the first time and the current-limited charging time of the battery further includes: if the difference between the first time and the current-limited charging time of the battery is within a set range, determining the preset start-up temperature and the first time as the start-up temperature and the start-up time of the temperature control system; if the difference between the first time and the current-limited charging time of the battery is not within the set range, correcting the preset start-up temperature and the first time to obtain a corrected temperature and a corrected time, and determining the start-up temperature and the start-up time of the temperature control system based on the corrected temperature and the corrected time.

[0018] Optionally, the step of correcting the preset start-up temperature and the first time to obtain the corrected temperature and the corrected time, and determining the start-up temperature and the start-up time of the temperature control system based on the corrected temperature and the corrected time, further includes: when the difference between the corrected time and the current-limited charging time of the battery is within the set range, determining the corrected temperature and the corrected time as the start-up temperature and the start-up time of the temperature control system.

[0019] Optionally, the preset start-up temperature can be corrected using a binary method, so that the difference between the correction time and the current-limited charging time of the battery is within the set range.

[0020] Optionally, the correction time is determined by the following method: determining the heat generation power of the battery during charging based on the equivalent internal resistance and charging current of each cell in the battery; determining a fifth time required for the battery to reach the correction temperature from the initial temperature based on the heat generation power, the specific heat capacity of the battery, and the battery mass; determining a sixth time required for the battery to reach the current-limiting temperature from the correction temperature based on the heat generation power, the cooling power of the temperature control system, the specific heat capacity of the battery, and the battery mass; and determining the correction time as the sum of the fifth time and the sixth time.

[0021] Optionally, the correction time is determined by the following formula:

[0022]

[0023] P charge =I c1 2 r 等效 n,

[0024] Where t1' is the correction time, ΔT2' is the temperature difference between the initial temperature and the correction temperature, ΔT3' is the temperature difference between the correction temperature and the current-limiting temperature, C is the specific heat capacity of the battery, m is the mass of the battery, and P charge P is the heating power. ac The cooling power; I c1 For the charging current, r 等效 The equivalent internal resistance is n, and the number of cells in the battery is n.

[0025] On the other hand, the present invention also provides a battery temperature control system applied to the battery temperature control method described above. The battery temperature control system includes: a first time determination module, used to determine the first time required for the battery to reach the current-limiting temperature from the initial temperature based on the initial temperature of charging the battery and the preset opening temperature of the temperature control system; and an opening parameter determination module, used to determine the opening temperature and opening time of the temperature control system based on the first time and the current-limiting charging time of the battery.

[0026] On the other hand, the present invention also provides a battery management system, the battery management system including the battery temperature control system as described above.

[0027] On the other hand, the present invention also provides a vehicle including the battery temperature control system described above.

[0028] Through the above technical solution, the battery temperature control method of this invention helps to achieve efficient battery charging. Currently, operating the cooling system at a fixed temperature point often results in insufficient cooling, leading to current limiting during battery charging and preventing full utilization of the battery's charging performance. This results in reduced charging efficiency and unnecessarily extended charging time. However, this invention can dynamically advance the start-up time of the cooling system based on the current SOC and temperature information of the power battery.

[0029] On the other hand, it helps avoid unnecessary power consumption in the battery cooling system: existing battery cooling strategies use a fixed-on, fixed-off temperature control system, which cannot be precisely controlled according to battery performance. This causes the cooling to fluctuate between over-cooling and under-cooling, failing to properly match the battery's charging characteristics and resulting in unnecessary power consumption. This invention, based on a control algorithm, estimates the optimal operating temperature of the cooling system and activates it at the appropriate time to cool the battery, avoiding unnecessary power consumption caused by prolonged operation of the cooling system.

[0030] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0031] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings:

[0032] Figure 1 This is a schematic flowchart of a battery temperature control method according to an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the allowable charging current configuration of a battery under different SOC conditions according to an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of a battery temperature control system according to an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of a battery management system according to an embodiment of the present invention. Detailed Implementation

[0036] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0037] This invention first provides a battery temperature control method, such as... Figure 1As shown, the determination method may include steps S110-S120.

[0038] Step S110: Based on the initial temperature of the battery being charged and the preset start temperature of the temperature control system, determine the first time required for the battery to reach the current limiting temperature from the initial temperature.

[0039] The initial temperature is the battery temperature when it begins charging, which is related to the ambient temperature in different scenarios. For example, the initial temperature can be set to 25°C, while in a colder environment it can be set to 10°C.

[0040] As charging time increases, battery temperature and SOC rise accordingly, eventually reaching the current limit. Therefore, a current-limiting temperature needs to be set for the battery. This temperature characterizes the temperature at which the charging current is initially limited, indicating that high-current charging should not be performed above a certain temperature. The current-limiting temperature is usually related to the battery model and battery settings. For example, a current-limiting temperature of 45°C can be used, while other types of batteries may use current-limiting temperatures of 40°C, 50°C, or other temperatures.

[0041] The preset start-up temperature is usually set based on empirical values. However, it should be understood that it should fall between the initial temperature and the current-limiting temperature; that is, it should be higher than the initial temperature and lower than the current-limiting temperature. For example, a preset start-up temperature of 35℃ can be chosen.

[0042] In one embodiment, the first moment can be determined by the following method:

[0043] Step S111: Determine the heat generation power of the battery during charging based on the equivalent internal resistance and charging current of each cell in the battery.

[0044] Step S112: Based on the heating power, the specific heat capacity of the battery, and the battery mass, determine the third time required for the battery to reach the preset start-up temperature from the initial temperature.

[0045] Step S113: Based on the heating power, the cooling power of the temperature control system, the specific heat capacity of the battery, and the battery mass, determine the fourth time required for the battery to reach the current-limiting temperature from the preset start-up temperature; and

[0046] Step S114: The sum of the third time and the fourth time is determined as the first time.

[0047] For example, the first time t1 can be determined by the following formula:

[0048]

[0049] P charge =I c1 2 r 等效 n,

[0050] Where ΔT2 is the temperature difference between the initial temperature and the preset start-up temperature, ΔT3 is the temperature difference between the preset start-up temperature and the current-limiting temperature, C is the specific heat capacity of the battery, m is the battery mass, and P... charge P is the heating power. ac For cooling power; I c1 For the charging current, r 等效 Let n be the equivalent internal resistance of each cell in the battery, and n be the number of cells in the battery.

[0051] Prior to step S110, the battery temperature control method may further include:

[0052] Step S101: When the battery is being charged and the temperature control system is not enabled, determine the second time required for the battery to reach the current-limiting temperature from the initial temperature.

[0053] Step S102: If the second time is greater than or equal to the current-limited charging time of the battery, the temperature control system is not activated.

[0054] In step S103, if the second time is less than the current-limited charging time of the battery, the temperature control system is activated.

[0055] In one embodiment, the second time can be determined by the following method:

[0056] Determine the heat generation power of the battery during charging based on the equivalent internal resistance and charging current of each cell; and

[0057] The second time is determined based on the heating power, initial temperature, current-limiting temperature, specific heat capacity of the battery, and battery mass.

[0058] For example, the second time t2 can be determined by the following formula:

[0059]

[0060] P charge =I c1 2 r 等效 n,

[0061] Where ΔT1 is the temperature difference between the initial temperature and the current-limiting temperature, C is the specific heat capacity of the battery, m is the mass of the battery, and P charge I is the heating power; c1 For the charging current, r 等效 Let n be the equivalent internal resistance of each cell in the battery, and n be the number of cells in the battery.

[0062] The purpose of adding this step is to confirm whether it is necessary to optimize the preset start temperature of cooling before implementing the battery temperature control method of the present invention. If the calculated second time is greater than the battery's current-limiting charging time, it means that without temperature control, the battery temperature has not yet risen to the current-limiting temperature when the current-limiting charging time is reached.

[0063] Therefore, in this case, it is not necessary to activate the temperature control system. This situation occurs in applications with low initial temperatures, such as those with an initial temperature of 10°C or lower.

[0064] Step S120: Determine the start-up temperature and start-up time of the temperature control system based on the first time and the current-limited charging time of the battery.

[0065] Step S120 may further include:

[0066] Step S121: If the difference between the first time and the current-limited charging time of the battery is within the set range, the preset start-up temperature and the first time are determined as the start-up temperature and start-up time of the temperature control system.

[0067] Step S122: If the difference between the first time and the current-limited charging time of the battery is not within the set range, the preset start-up temperature and the first time are corrected to obtain the corrected temperature and corrected time, and the start-up temperature and start-up time of the temperature control system are determined based on the corrected temperature and corrected time.

[0068] The corrected temperature should be between the initial temperature and the current-limiting temperature, just like the preset start-up temperature; that is, it should be higher than the initial temperature and lower than the current-limiting temperature. For example, the corrected temperature can be set to 40℃ or 43℃.

[0069] In one embodiment, the set interval can be adaptively selected according to the actual application. Generally, if the difference between the first time and the battery's current-limited charging time is within 6 minutes, the preset start-up temperature does not need to be corrected. Otherwise, the preset start-up temperature needs to be corrected to meet the optimal charging state. If more precise control of the cooling start-up timing is desired, the value of the set interval can be further reduced to 3 minutes or even 1 minute, thereby maximizing the utilization of battery charging performance while minimizing the energy consumption of the cooling system.

[0070] In one embodiment, a binary search method can be used to correct the preset activation temperature. The correction direction is determined by the difference between the first time interval and the battery's current-limited charging time. If the first time interval is greater than the battery's current-limited charging time, it means that the battery temperature has not yet risen to the current-limited temperature when the current-limited charging time is reached, resulting in wasted cooling power. Therefore, the activation of the temperature control system should be delayed; that is, the preset activation temperature should be corrected to the right, to a greater extent.

[0071] Conversely, if the initial charging time is less than the battery's current-limiting time, it means that the battery's temperature has already risen to the current-limiting temperature before the current-limiting charging time is reached, and the temperature control system is not functioning properly. Therefore, the temperature control system should be activated earlier; that is, the preset activation temperature should be adjusted to the left and to a smaller extent.

[0072] In step S122, when the battery is recharged and the temperature control system is activated at the corrected temperature, the following steps can be used to determine the correction time required for the battery to reach the current-limiting temperature from the initial temperature, referring to the calculation method in step S110 above:

[0073] 1) Determine the fifth time required for the battery to reach the corrected temperature from the initial temperature based on the heating power, specific heat capacity, and mass of the battery;

[0074] 2) Based on the heating power, the cooling power of the temperature control system, the specific heat capacity of the battery, and the battery mass, determine the sixth time required for the battery to reach the current-limiting temperature from the corrected temperature; and

[0075] 3) The sum of the fifth time and the sixth time is determined as the correction time.

[0076] For example, the correction time t1' can be determined by the following formula:

[0077]

[0078] P charge =I c1 2 r 等效 n,

[0079] Where ΔT2' is the temperature difference between the initial temperature and the corrected temperature, ΔT3' is the temperature difference between the corrected temperature and the current-limiting temperature, C is the specific heat capacity of the battery, m is the battery mass, and P... charge P is the heating power. ac For cooling power; I c1 For the charging current, r 等效 Let n be the equivalent internal resistance of each cell in the battery, and n be the number of cells in the battery.

[0080] In step S122, if the difference between the correction time and the current-limited charging time of the battery is within a set range, the correction temperature and correction time can be determined as the start-up temperature and start-up time of the temperature control system.

[0081] Through the above technical solution, the battery temperature control method of this invention helps to achieve efficient battery charging. Currently, operating the cooling system at a fixed temperature point often results in insufficient cooling, leading to current limiting during battery charging and preventing full utilization of the battery's charging performance. This results in reduced charging efficiency and unnecessarily extended charging time. However, this invention can dynamically advance the start-up time of the cooling system based on the current SOC (State of Charge) and temperature information of the power battery.

[0082] On the other hand, it helps avoid unnecessary power consumption in the battery cooling system: existing battery cooling strategies use a fixed-on, fixed-off temperature control system, which cannot be precisely controlled according to battery performance. This causes the cooling to fluctuate between over-cooling and under-cooling, failing to properly match the battery's charging characteristics and resulting in unnecessary power consumption. This invention, based on a control algorithm, estimates the optimal operating temperature of the cooling system and activates it at the appropriate time to cool the battery, avoiding unnecessary power consumption caused by prolonged operation of the cooling system.

[0083] Through the above-described solution, this invention uses a designed algorithm to predict the activation time of the battery temperature control system, avoiding prolonged charging time and energy waste caused by premature activation due to untimely activation of the temperature control system. Furthermore, it fully considers the impact of current ambient temperature and cell SOC values ​​on battery charging performance, calculating the optimal activation time of the temperature control system in real time, thereby enhancing control accuracy. In addition, this invention can fully utilize the battery's charging performance, avoid unnecessary power consumption by the cooling system, and more accurately calculate the activation temperature of the temperature control system under different environments, making control more rational and precise.

[0084] The following provides a specific implementation method using a certain model of battery as an example. The preset values ​​of the battery's configuration parameters are shown in Table 1:

[0085] Table 1, Preset values ​​for battery configuration parameters:

[0086]

[0087] Other preset parameters are: dual-pack vehicle, 200 pack cells, initial SOC of 0%, initial battery temperature of 25°C, preset start-up temperature T of cooling system of 35°C, current limiting temperature of 45°C, and cooling power of 10kW.

[0088] in addition, Figure 2The diagram shows the permissible charging current values ​​for the battery under different SOC conditions, controlled by the BMC (Battery Management Controller) within a temperature range of 25–45°C. It can be seen that the charging current is 200A before the battery reaches 65% charge, and decreases to 80A after reaching 65%. Furthermore, the charging current decreases to 65A and 40A respectively after the battery reaches 85% and 90% charge. In addition, other permissible charging current values ​​can be set depending on the specific type of battery pack.

[0089] In one embodiment, firstly, it is necessary to calculate the heat generation power of the battery when the SOC is 0%, for example, when the battery is charged with a charging current of 200A:

[0090] P charge =I c1 2 r 等效 n = (200) 2 ×(0.9×10 -3 )×400×10 -3 =14.4kW,

[0091] Next, it is necessary to calculate the first time required for the battery to reach the current-limiting temperature from its initial temperature when the temperature control system is activated during battery charging. The time required for the battery to reach the preset activation temperature from its initial temperature, and the time required to reach the current-limiting temperature from the preset activation temperature, can be calculated separately.

[0092] Specifically, the time t0 required for the battery to rise from an initial temperature of 25°C to a preset start-up temperature of 35°C is:

[0093]

[0094] The increase in battery charge Δ during this process SOC The value is:

[0095] Δ SOC1 =200 × 0.54 ÷ 491 = 22.00%

[0096] And, through cooling power P ac =10kW, calculate the time t required for the battery to rise from the preset start-up temperature of 35℃ to the current-limiting temperature of 45℃ after the cooling is activated at the preset start-up temperature of 35℃. 11 for:

[0097]

[0098] Therefore, the first time t1 required for the battery to rise from the initial temperature of 25°C to the current-limiting temperature of 45°C, under the condition that the battery is charged at the maximum allowable current and the cooling is activated when the battery temperature reaches 35°C, is:

[0099] t1 = t0 + t 11 =0.54 + 1.76 = 2.3h

[0100] It can be seen that when the cooling system is turned on at 35°C, the battery needs to continue charging at the maximum allowable current for 2.3 hours before reaching the current-limiting temperature. By referring to the full-power charging time calculation table in Table 2, it can be found that after full-power charging t4 = 1.6 hours, the battery will reach 65% of the current-limiting SOC and begin to limit the charging current.

[0101] Table 2, Calculation table for full-power charging time:

[0102]

[0103] The comparison shows that t4 < t1, indicating that if the cooling system is activated when the battery temperature reaches 35°C, there will be no limitation on charging current due to excessive battery temperature within 1.6 hours after charging begins. Furthermore, the difference between the two is 0.7 hours (42 minutes), which is significantly greater than the preset interval of 6 minutes. It also shows that if cooling is activated at the current preset temperature of 35°C, the battery temperature is actually below 45°C when reaching 65% current-limited SOC, resulting in unnecessary power loss. This suggests that the activation temperature of the cooling system can be further adjusted.

[0104] The specific direction of correction can be determined by the following: calculating the second time required for the battery to reach the current-limiting temperature from the initial temperature when the temperature control system is not enabled during battery charging.

[0105] The second time t2 may include the time t0 = 0.54h required for the battery to reach the preset turn-on temperature from the initial temperature, and the time t0 required for the battery to reach the current-limiting temperature from the preset turn-on temperature. 12 .

[0106] Among them, the battery charge Δ increases during time t0. SOC The value is;

[0107] Δ SOC1 =200 × 0.54 ÷ 491 = 22.00%

[0108] Additionally, the time t required for the battery to rise from the preset start-up temperature of 35°C to the current-limiting temperature of 45°C 12 for:

[0109]

[0110] Therefore, the second time t2 required for the battery to rise from the initial temperature of 25°C to the current-limiting temperature of 45°C during this process is:

[0111] t2 = t0 + t 12 =1.08h,

[0112] Simultaneously calculate the increase Δ during this process. SOC The value is:

[0113] Δ SOC2 =200 × 1.08 ÷ 491 = 43.99%,

[0114] The SOC (State of Charge) is defined as the battery capacity at which the battery is charged to the temperature-limited current condition without the temperature control system activated. 充电后 ,but:

[0115] SOC 充电后 =Δ SOC2 =43.99%,

[0116] According to the full-power charging time calculation table in Table 2, the time t3 required to charge the battery to 65% is 1.6 hours.

[0117] Since t2 < t3, this means that without activating the cooling system, the charging current will be limited due to excessively high battery temperature after 1.08 hours of charging. At this point, the charging capacity has not yet reached 65% of the current-limiting capacity, therefore the cooling system needs to be activated. Furthermore, based on the calculations above, when the cooling system is activated at the preset activation temperature of 35℃, it will take another 2.3 hours of charging at the maximum allowable current to reach the current-limiting temperature. Therefore, the preset activation temperature needs to be adjusted later to conserve power from the cooling system and avoid unnecessary energy loss.

[0118] In this embodiment, the optimal start-up temperature of the temperature control system can be obtained by bisection convergence. For example, the midpoint between 35°C and 45°C, 40°C, can be taken as the first correction temperature T', and then the correction time required for the battery to reach the current-limiting temperature from the initial temperature when the temperature control system is turned on at the correction temperature during charging can be recalculated.

[0119] Specifically, the time t0' required for the battery to rise from the initial temperature of 25°C to the corrected temperature of 40°C is:

[0120]

[0121] Then, through the cooling power P ac =10kW, calculate the correction time t required for the battery to rise from the preset start-up temperature of 40℃ to the current-limiting temperature of 45℃ after the battery reaches the correction temperature of 40℃ and the cooling is turned on.11 'for:

[0122]

[0123] Therefore, the corrected time t1' required for the battery to rise from the initial temperature of 25°C to the current-limiting temperature of 45°C, under the condition that the battery is charged at the maximum allowable current and the cooling is activated when the battery temperature reaches 40°C, is:

[0124] t1'=t0'+t 11 = 0.81 + 0.88 = 1.69h

[0125] The difference between the correction time t1' (1.69h) and the current-limiting charging time t4 (1.6h) is 0.09h, or 5.4min, which meets the preset interval of 6min. Therefore, the correction temperature of 40℃ can be determined as the start-up temperature of the temperature control system.

[0126] Alternatively, the following formula can be used for calculation:

[0127] Given that without cooling, the time taken to charge the battery to 40°C at the maximum allowable current is t0' = 0.81 h, and the remaining time to continue charging at the maximum allowable current to 65% SOC is:

[0128] t5=t4-t0'=1.6-0.81=0.79h,

[0129] At this point, it is also necessary to calculate the battery temperature change ΔT after the corrected temperature of 40℃ is reached and the cooling is turned on, and charging continues for time t5:

[0130]

[0131] We can obtain ΔT = 4.47℃, which means that when the cooling system is turned on at the corrected temperature T' = 40℃, the battery temperature at the current-limited SOC is only 44.47℃, which is 0.53℃ different from the current-limited temperature of 45℃. The two are very close, so the corrected temperature of 40℃ can also be determined as the start temperature of the temperature control system.

[0132] Therefore, when the automatic cooling capacity estimation function is enabled, the cooling can be turned on when the battery temperature reaches 40°C, ensuring that the charging power is not limited by temperature. After 1.6 hours of charging, the temperature and SOC reach the current limit value almost simultaneously, maximizing the use of battery charging performance while minimizing the energy consumption of the cooling system.

[0133] In addition, to more precisely control the timing of the cooling system's activation, the binary search method can be repeated to obtain a more accurate start-up temperature. For example, with a set interval of 3 minutes, the calculated start-up temperature of the temperature control system is 41°C, and the difference between the correction time and the current-limiting charging time is 1.92 minutes.

[0134] With a set interval of 1 minute, the calculated start-up temperature of the temperature control system is 40.75℃. The difference between the correction time and the current-limited charging time is 0.09 minutes, or 5.4 seconds. It can be basically considered that the correction time and the current-limited charging time are synchronized.

[0135] On the other hand, the present invention also provides a battery temperature control system 300, applied to the battery temperature control method described above, such as... Figure 3 As shown, the battery temperature control system 300 may include:

[0136] The first-time determination module 310 is used to determine the first time required for the battery to reach the current-limiting temperature from the initial temperature based on the initial temperature of the battery being charged and the preset opening temperature of the temperature control system.

[0137] The start-up parameter determination module 320 is used to determine the start-up temperature and start-up time of the temperature control system based on the first time and the current-limited charging time of the battery.

[0138] On the other hand, the present invention also provides a battery management system 400, which includes the battery temperature control system 300 as described above.

[0139] In addition, such as Figure 4 As shown, the battery management system 400 may further include:

[0140] Temperature sensor 410 is used to acquire the battery temperature in the battery management system;

[0141] Current sensor 420 is used to acquire current values ​​in the battery management system;

[0142] Timer 430 is used to obtain the charging time from the battery management system;

[0143] The charging station 440 is used to generate a charging start signal when the battery is charging;

[0144] Instrument 450 is used to generate a discharge start signal when using battery power; and

[0145] BMC460 is used to acquire signals collected or generated by temperature sensor 410, current sensor 420, timer 430, charging pile 440 and instrument 450, and to determine the start-up temperature of the temperature control system using the battery temperature control method described above.

[0146] Furthermore, the battery management controller can control the air conditioner 470 to cool the battery when it detects that the battery temperature has reached the activation temperature; and control the air conditioner 470 to turn off to stop cooling the battery when it detects that the battery temperature is lower than the activation temperature.

[0147] Furthermore, the workflow of this invention can be summarized as follows, with the aid of the battery management system 400 and its various components:

[0148] S01, BMC controls the vehicle to charge;

[0149] S02, the battery communication acquisition unit transmits the current battery information to the BMC;

[0150] S03, the current sensor transmits the current battery information to the BMC;

[0151] S04, BMC determines and calculates cooling / heating time;

[0152] S05, without turning on the cooling / heating, calculate the time t2 required to reach the flow-limiting temperature based on the current temperature and SOC value;

[0153] S06, Calculate the battery SOC after continuous charging for t2 times at the current maximum allowable current. 充电后 The value;

[0154] S07, comparing SOC 充电后 and SOC 限流 The magnitude of the value, if SOC 充电后 <SOC 限流 If yes, proceed to step S09; otherwise, proceed to step S08.

[0155] S08, no cooling required;

[0156] S09, temperature current limiting is triggered earlier than SOC current limiting, resulting in the battery charging performance not being fully utilized, proceed to the next calculation;

[0157] S10: When the battery reaches the preset start-up temperature T, the cooling / heating is turned on. Based on the current temperature and SOC value, the time t1 required to reach the current limiting temperature is calculated.

[0158] S11, look up the table to get the charging time t4 required to reach the current-limited SOC at full power charging;

[0159] S12, compare the values ​​of time t4 and t1. If t1 > t4, then proceed to step S14; otherwise, proceed to step S13.

[0160] S13 requires the cooling system to be kept on at all times;

[0161] S14, The preset opening temperature is corrected using the binary method to obtain the optimal temperature control system opening temperature T';

[0162] S15, set the correction temperature T' to the trigger temperature for the temperature control system to start.

[0163] The meanings of the parameters mentioned above are as follows:

[0164] t2: The time required for the battery to reach its current-limiting temperature by charging at the maximum charging current, based on the current battery temperature and SOC value, without activating the temperature control system.

[0165] t1: Under the condition that the temperature control system is activated at the preset start temperature, the time required for the battery to reach the current limit temperature by charging at the maximum charging current according to the current battery temperature and SOC value.

[0166] t4: Refer to the table to find the time required for the battery to reach the current limit SOC when charging at full power;

[0167] T': The optimal trigger temperature for the temperature control system to start after correction.

[0168] On the other hand, the present invention also provides a vehicle including the battery temperature control system described above.

[0169] The beneficial effects of the battery temperature control system and battery management system provided by this invention can be referred to the above description of the battery temperature control method, and will not be repeated here.

[0170] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0171] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A battery temperature control method, characterized in that, The battery temperature control method includes: Based on the initial temperature of the battery being charged and the preset start temperature of the temperature control system, the first time required for the battery to reach the current limiting temperature from the initial temperature is determined, wherein the initial temperature is the battery temperature when the battery starts charging, and the preset start temperature is greater than the initial temperature and less than the current limiting temperature. Based on the first time and the current-limited charging time of the battery, the activation temperature and activation time of the temperature control system are determined. The current-limited charging time is obtained by referring to a full-power charging time calculation table. The step of determining the start-up temperature and start-up time of the temperature control system based on the first time and the current-limited charging time of the battery includes: if the difference between the first time and the current-limited charging time of the battery is not within a set range, correcting the preset start-up temperature and the first time to obtain a corrected temperature and a corrected time, and determining the start-up temperature and start-up time of the temperature control system based on the corrected temperature and the corrected time. The battery temperature control method further includes: using a binary search method to correct the preset start-up temperature, such that the difference between the correction time and the current-limited charging time of the battery is within a set range. The correction time is determined by the following method: The heat generation power of the battery during charging is determined based on the equivalent internal resistance and charging current of each cell in the battery. Based on the heating power, the specific heat capacity of the battery, and the battery mass, determine the fifth time required for the battery to reach the corrected temperature from the initial temperature; Based on the heating power, the cooling power of the temperature control system, the specific heat capacity of the battery, and the battery mass, determine the sixth time required for the battery to reach the current-limiting temperature from the corrected temperature; and The sum of the fifth time and the sixth time is determined as the corrected time.

2. The battery temperature control method according to claim 1, characterized in that, Before determining the first time required for the battery to reach the current-limiting temperature from the initial temperature based on the initial temperature of charging the battery and the preset start-up temperature of the temperature control system, the battery temperature control method further includes: When the battery is being charged and the temperature control system is not enabled, a second time is determined that the battery needs to reach the current-limiting temperature from the initial temperature. If the second time is greater than or equal to the current-limited charging time of the battery, the temperature control system is not activated; If the second time is less than the current-limited charging time of the battery, then the temperature control system is activated.

3. The battery temperature control method according to claim 2, characterized in that, The second time is determined by the following method: The heat generation power of the battery during charging is determined based on the equivalent internal resistance and charging current of each cell in the battery; and The second time is determined based on the heating power, the initial temperature, the current-limiting temperature, the specific heat capacity of the battery, and the battery mass.

4. The battery temperature control method according to claim 3, characterized in that, The second time is determined by the following formula: in, For the second time, The temperature difference between the initial temperature and the current-limiting temperature. The specific heat capacity of the battery is given by [reference needed]. The mass of the battery, The heating power; The charging current, The equivalent internal resistance is... The number of cells in the battery.

5. The battery temperature control method according to claim 1, characterized in that, The first time is determined by the following method: The heat generation power of the battery during charging is determined based on the equivalent internal resistance and charging current of each cell in the battery. Based on the heating power, the specific heat capacity of the battery, and the battery mass, determine the third time required for the battery to reach the preset start-up temperature from the initial temperature; Based on the heating power, the cooling power of the temperature control system, the specific heat capacity of the battery, and the mass of the battery, determine the fourth time required for the battery to reach the current limiting temperature from the preset start-up temperature; as well as The sum of the third time and the fourth time is determined as the first time.

6. The battery temperature control method according to claim 5, characterized in that, The first time is determined by the following formula: in, For the first time, The temperature difference between the initial temperature and the preset opening temperature. The temperature difference between the preset start-up temperature and the current-limiting temperature. The specific heat capacity of the battery is given by [reference needed]. The mass of the battery, The heating power, The cooling power; The charging current, The equivalent internal resistance is... The number of cells in the battery.

7. The battery temperature control method according to claim 1, characterized in that, The step of determining the start-up temperature and start-up time of the temperature control system based on the first time and the current-limited charging time of the battery further includes: If the difference between the first time and the current-limited charging time of the battery is within the set range, the preset start-up temperature and the first time are determined as the start-up temperature and start-up time of the temperature control system.

8. The battery temperature control method according to claim 7, characterized in that, The step of correcting the preset start-up temperature and the first time to obtain the corrected temperature and the corrected time, and determining the start-up temperature and the start-up time of the temperature control system based on the corrected temperature and the corrected time, further includes: When the difference between the correction time and the current-limited charging time of the battery is within the set range, the correction temperature and the correction time are determined as the start-up temperature and the start-up time of the temperature control system.

9. The battery temperature control method according to claim 1, characterized in that, The correction time is determined by the following formula: in, The correction time is... The temperature difference between the initial temperature and the corrected temperature. The temperature difference between the correction temperature and the current-limiting temperature. The specific heat capacity of the battery is given by [reference needed]. The mass of the battery, The heating power, The cooling power; The charging current, The equivalent internal resistance is... The number of cells in the battery.

10. A battery temperature control system, applied to the battery temperature control method according to any one of claims 1-9, characterized in that, The battery temperature control system includes: The first-time determination module is used to determine, based on the initial charging temperature of the battery and the preset activation temperature of the temperature control system, the first time required for the battery to reach the current-limiting temperature from the initial temperature; and The start-up parameter determination module is used to determine the start-up temperature and start-up time of the temperature control system based on the first time and the current-limited charging time of the battery.

11. A battery management system, characterized in that, The battery management system includes the battery temperature control system according to claim 10.

12. A vehicle, characterized in that, The vehicle includes the battery temperature control system according to claim 10.

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