Thermal management method for prolonging service life of battery of electric vehicle

Abstract

The invention belongs to the technical field of automobile battery management, and particularly relates to a thermal management method for prolonging the service life of a battery of an electric automobile, which comprises the following steps: in a charging state, a BMS (Battery Management System) detects Tmax and SOC (State of Charge) information in real time; if Tmax is greater than or equal to the first set temperature and SOC is greater than or equal to the set electric quantity; calculating the time t1 required for charging until SOC is equal to 100%; according to the calibrated thermal management parameter table, calculating the time t2 required for reducing the temperature of the battery from Tmax > = the first set temperature to Tmax = the second set temperature in the thermal management state; when t2 is smaller than or equal to t1 and SOC is equal to 100%, the Tmax is reduced to the second set temperature of the target temperature, when t2 is larger than or equal to t1, the charging rate is reduced, and when SOC is equal to 100%, the Tmax is reduced to the second set temperature of the target temperature. According to the technical scheme, liquid cooling and heating management is started at the end of charging of the battery pack, and the temperature at the end of charging is controlled within an ideal range through temperature control.

Description

Technical Field

[0001] This invention belongs to the field of automotive battery management technology, specifically relating to a thermal management method for extending the lifespan of electric vehicle batteries. Background Technology

[0002] Currently, lithium iron phosphate batteries used in new energy commercial vehicles are already capable of 2C charging. Due to their high current, even with a liquid-cooled thermal management system, the temperature rise at the end of charging is significant. Typically, charging begins at room temperature (25°C) and continues from 0% SOC to 100%, reaching a temperature of approximately 50-55°C at the end of charging. If the vehicle's thermal management system is not activated after overnight charging, the battery pack will be left idle. This means the initial temperature for the battery pack's calendar lifespan is above 50°C, which will significantly impact the battery's calendar lifespan.

[0003] In existing charging management technologies, after charging is completed, the vehicle loses high voltage and thermal management is no longer activated, thus failing to lower the temperature of the power battery. As a result, the battery pack temperature remains high after charging, leading to a faster decline in the battery pack's calendar life when it is left idle. Summary of the Invention

[0004] The purpose of this invention is to provide a thermal management method for extending the battery life of electric vehicles. Liquid cooling thermal management is activated at the end of the battery pack charging process to reduce the temperature at the end of charging to between 25-35°C, thereby solving the problem of the degradation of calendar life when the vehicle is stationary.

[0005] To achieve the above objectives, this application employs the following technical solution:

[0006] A thermal management method for extending the battery life of an electric vehicle includes the following steps:

[0007] S1. During charging, the BMS continuously monitors Tmax and SOC information.

[0008] S2. If Tmax ≥ first set temperature and SOC ≥ set power;

[0009] S3. Calculate the time t1 required to charge to SOC=100%;

[0010] S4. Based on the calibrated thermal management parameter table, calculate the time t2 required for the battery temperature to decrease from Tmax≥first set temperature to Tmax=second set temperature under thermal management conditions, and proceed to step S5.

[0011] S5. When t2≤t1, and SOC=100%, Tmax is reduced to the second set temperature of the target temperature. When t2≥t1, the charging rate is reduced. When SOC=100%, Tmax is reduced to the second set temperature of the target temperature.

[0012] Furthermore, in step S2, the first set temperature is 45°C and the set power is 90%.

[0013] Furthermore, in step S2, the first set temperature and the set power need to be determined in conjunction with the ambient temperature, and then calibrated and stored in the BMS.

[0014] Furthermore, in step S3, the time t1 required to charge to SOC=100% is calculated, a battery pack calibration charging pattern is generated, and the battery pack calibration charging pattern is stored in the BMS.

[0015] Furthermore, the second set temperature is lower than the first set temperature.

[0016] Furthermore, in step S5, when t2≥t1, the charging rate is reduced according to the ratio of t1 / t2.

[0017] The beneficial effects of this invention are:

[0018] This technical solution enables liquid cooling thermal management to be activated at the end of battery pack charging, and the temperature at the end of charging is controlled within an ideal range through temperature control. Attached Figure Description

[0019] Figure 1 This is a diagram illustrating the thermal management strategy of the present invention. Detailed Implementation

[0020] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings. The following embodiments are merely exemplary and can only be used to explain and illustrate the technical solution of the present invention, and should not be construed as limiting the technical solution of the present invention.

[0021] This technical solution addresses the issue of activating liquid cooling thermal management at the end of battery pack charging and controlling the battery pack temperature within an ideal range at the end of charging through temperature control.

[0022] The reality addressed by this technical solution is that all products using rechargeable batteries currently face the same problem: heat is inevitably generated during charging, whether it's a mobile phone, computer, or electric vehicle. Taking a mobile phone as an example, the phone gets very hot during or after charging, even with a small, single battery. Electric vehicles, on the other hand, use a large number of batteries to form a battery pack, and the charging voltage is higher, generating even more heat. Without proper thermal management, this heat dissipates slowly, especially in high ambient temperatures. This can directly cause thermal changes in the battery fluid, positive electrode, and negative electrode materials, leading to a significant reduction in the battery pack's calendar life.

[0023] like Figure 1 As shown, during charging, the BMS continuously monitors the battery pack's maximum temperature Tmax and real-time SOC information. In this embodiment, the example of a maximum charging temperature Tmax ≥ 45℃ and an SOC ≥ 90% is used for illustration. In the technical solution of this application, the battery pack temperature varies after charging is completed under different ambient temperatures. Therefore, it is necessary to monitor Tmax at different ambient temperatures or specific SOCs for more precise thermal management.

[0024] The battery pack charging was calibrated, and a battery pack calibration charging pattern was prepared as shown in Table 1. The battery pack calibration charging pattern was stored in the BMS. Then, based on the battery pack calibration charging pattern, the time t1 required to charge to SOC=100% was determined.

[0025] Thermal management is performed on the battery pack temperature at a specific time before the end of charging. Specific thermal management parameters need to be calibrated in advance. In this embodiment, a second set temperature Tmax = 35℃ is used as an example. The pre-calibrated thermal management parameters are shown in Table 2. Here, after the battery pack charging is completed, to avoid reducing the battery pack's calendar life, the temperature of the battery pack is reduced to the second set temperature through thermal management. In this application, the second set temperature can be changed according to specific circumstances; for example, it can be set to 38℃, 33℃, etc.

[0026] Calculations show that the time t2 required for thermal management to reduce Tmax from 45℃ to 35℃ is ≤ t1. That is, when SOC = 100%, the battery pack will be cooled to the target temperature, i.e., the second set temperature of 35℃.

[0027] When t2 ≥ t1, the charging rate is reduced by multiplying t1 / t2 by the charging rate. When SOC = 100%, the first set temperature Tmax = 45℃ is determined to be reduced to the target temperature of 35℃. This application addresses the issue that when t2 is longer than t1, the charging rate is appropriately reduced based on the t1 / t2 ratio to ensure that the target temperature is reached when SOC = 100%.

[0028] Table 1

[0029]

[0030] In this embodiment, Table 1 shows the charging pattern of the battery pack, with influencing factors including temperature, SOC, and charging rate. In Table 1, the values, such as 2.00, represent the charging rate (2C), and SOC refers to the state of charge.

[0031] In this embodiment, at 35°C, the charging rate for 90% SOC is 0.9C, the charging rate for 95% SOC is 0.55C, and the charging rate for 100% SOC is 0.33C. The charging time for SOC = 90% - 95% is (1 / 0.9) * 60 * 0.05 = 3.3 min; the charging time for SOC = 90% - 95% is (1 / 0.55) * 60 * 0.05 = 5.5 min; and the charging time for SOC = 95% - 100% is (1 / 0.33) * 60 * 0.05 = 9.0 min.

[0032] Table 2 shows the thermal management parameters, including the temperature drop rate of the battery pack's Tmax at different temperatures. This value needs to be calibrated in the environmental chamber beforehand and stored in the BMS software.

[0033] Here, we will use Tmax=45℃ as an example for explanation:

[0034] Table 2

[0035]

[0036] When Tmax = 35℃:

[0037] Table 3

[0038]

[0039] The above are preferred embodiments of the present invention. The basic principles and advantages of the present invention have been shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from the spirit and scope of the present invention. All such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A thermal management method for extending the battery life of an electric vehicle, characterized in that, Includes the following steps: S1. During charging, the BMS continuously monitors Tmax and SOC information. S2. If Tmax ≥ first set temperature and SOC ≥ set power; S3. Calculate the time t1 required to charge to SOC=100%; S4. Based on the calibrated thermal management parameter table, calculate the time t2 required for the battery temperature to decrease from Tmax≥first set temperature to Tmax=second set temperature under thermal management conditions, and proceed to step S5. S5. When t2≤t1, and SOC=100%, Tmax is reduced to the second set temperature of the target temperature. When t2≥t1, the charging rate is reduced. When SOC=100%, Tmax is reduced to the second set temperature of the target temperature.

2. The thermal management method for extending the battery life of an electric vehicle according to claim 1, characterized in that, In step S2, the first set temperature is 45°C and the set power is 90%.

3. The thermal management method for extending the battery life of an electric vehicle according to claim 2, characterized in that, In step S2, the first set temperature and set power need to be determined based on the ambient temperature, and then calibrated and stored in the BMS.

4. The thermal management method for extending the battery life of an electric vehicle according to claim 1, characterized in that, In step S3, the time t1 required to charge to SOC=100% is calculated, a battery pack calibration charging pattern is created, and the battery pack calibration charging pattern is stored in the BMS.

5. The thermal management method for extending the battery life of an electric vehicle according to claim 1, characterized in that, The second set temperature is lower than the first set temperature.

6. The thermal management method for extending the battery life of an electric vehicle according to claim 1, characterized in that, In step S5, when t2≥t1, the charging rate is reduced according to the ratio of t1 / t2.

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