Battery thermal management control method based on working condition optimization

Abstract

A battery thermal management control method based on working condition optimization relates to the technical field of new energy vehicles, and dynamically adjusts a heating closing threshold TC of a battery thermal management system based on actual working conditions, so that the thermal management control method and the actual working conditions realize adaptive adjustment. According to the value obtaining method of the heating closing threshold TC, firstly, historical operation data are analyzed, the maximum discharging current value and the maximum charging current value under the actual working condition are extracted, then a battery charging and discharging MAP table is looked up, and the corresponding optimal heating closing threshold is determined, so that heating control of the self-adaptive working condition and the vehicle type is achieved, and the balance of the dynamic property and the economical efficiency is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicles, and particularly relates to a battery thermal management control method based on operating condition optimization. Background Art

[0002] As a core component of new energy vehicles, the performance of the power battery is crucial for the power performance and economy of the whole vehicle. The charge and discharge performance of the power battery is closely related to temperature. In a low-temperature environment, the battery capacity and power are greatly affected by temperature, mainly manifested as large attenuation of low-temperature power, limited charge and discharge power, and significant reduction in mileage, and there is also an easy risk of lithium plating safety. In order to improve the performance of the battery in a low-temperature environment, the prior art usually heats the battery in a fixed-threshold manner, that is, when the battery temperature is lower than a fixed heating start threshold, heating is started, and when the battery temperature is higher than a fixed heating stop threshold, heating is stopped.

[0003] However, the fixed-threshold heating method cannot be flexibly adjusted according to the actual operating condition requirements, resulting in overheating or insufficient heating of the power battery, so there are certain defects. When overheating occurs, energy is wasted and the economy of the whole vehicle is reduced; when heating is insufficient, the charge and discharge performance of the battery is limited, affecting the power performance of the whole vehicle. In addition, due to the different battery capacities configured for different vehicle models, the fixed-threshold heating method cannot meet the requirements of different vehicle models, nor can it achieve the best balance between power performance and economy. Summary of the Invention

[0004] The present invention provides a battery thermal management control method based on operating condition optimization, and its main purpose is to solve the problems existing in the prior art.

[0005] The present invention adopts the following technical solutions:

[0006] A battery thermal management control method based on operating condition optimization, the method for obtaining the heating stop threshold T of the battery thermal management system C comprises the following steps:

[0007] S1. Obtain M maximum discharge current values I dis and M maximum charge current values I chg of the vehicle under the actual operating condition, and store them into the I dis [M] array and the I chg [M] array respectively;

[0008] S2. Based on the I dis [M] array and the I chg [M] array, obtain the maximum discharge current value I dismax and the maximum charge current value I chgmax under the corresponding operating condition:

[0009]

[0010] In the formula: and are respectively the maximum and minimum values in the I dis [M] array, and are respectively the maximum and minimum values in the I chg [M] array;

[0011] S3. Check the battery charge and discharge MAP table to obtain the temperature T1 corresponding to k*I dismax and the 50% SOC point, and the temperature T2 corresponding to k*I chgmax and the 50% SOC point, and take the larger value of T1 and T2 to obtain the heating-off threshold T c ; where k represents a value-taking coefficient;

[0012] T c = max[T1, T2]

[0013] S4. Loop through steps S1 to S3 under actual working conditions to continuously update the heating-off threshold T c .

[0014] Furthermore, in step S1, the way to obtain the M maximum discharge current values I dis and the M maximum charge current values I chg is as follows: Sort all the discharge current values and charge current values of the vehicle during N days of operation under actual working conditions or during N charge and discharge cycles from large to small, and respectively take the first M discharge current values and the first M charge current values as the maximum discharge current value I dis and the maximum charge current value I chg and store them in the corresponding arrays.

[0015] Furthermore, the value range of N is N≥3, and the value range of M is M≥100.

[0016] Furthermore, the value range of k is 0.75 to 1.

[0017] Furthermore, the battery thermal management control method includes the following steps:

[0018] Step 10. Initialize the battery thermal management system to enter the shutdown mode;

[0019] Step 20. Continuously obtain the minimum temperature T min and the maximum temperature T max of the power battery, and judge the minimum temperature T minIs it lower than the heating start threshold T0? If the determination result is yes, execute step S30 to enter the heating mode; if the determination result is no, further determine whether the temperature difference △T of the power battery is higher than the second temperature threshold T2 and whether the power battery is a liquid heating configuration. If both are satisfied, execute step S40 to enter the self-circulation mode; otherwise, maintain the shutdown mode.

[0020] Step 30: Enter the heating mode, turn on the battery heating, and obtain the minimum temperature T of the power battery in real time min , and determine the minimum temperature T of the power battery min Is it higher than the heating shutdown threshold T C ? If the determination result is yes, further determine the heating configuration of the power battery. If the power battery is an electric heating configuration, enter the shutdown mode; if the power battery is a liquid heating configuration, execute step S40 to enter the self-circulation mode; if the determination result is no, maintain the heating mode.

[0021] Step S40: Enter the self-circulation mode, turn on the water pump circulation, and obtain the minimum temperature T min and the maximum temperature T max of the power battery in real time, and determine the minimum temperature T min of the power battery. Is it lower than the heating start threshold T0? If the determination result is yes, enter the heating mode; if the determination result is no, further determine whether the total self-circulation duration exceeds the set duration t or whether the maximum temperature T max of the power battery is higher than the third temperature threshold T3. If so, enter the shutdown mode; otherwise, maintain the self-circulation mode.

[0022] Furthermore, the heating start threshold T0 = the heating shutdown threshold T C - the first temperature threshold T1, and the value range of the first temperature threshold T1 is 3 to 5 °C.

[0023] Furthermore, the value range of the second temperature threshold T2 is 9 to 12 °C.

[0024] Furthermore, the value range of the set duration t is t ≥ 20 min.

[0025] Furthermore, the third temperature threshold T3 = the battery inlet temperature - the set temperature T4, and the value range of the set temperature T4 is 3 to 7 °C.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] 1. The present invention dynamically adjusts the heating shutdown threshold of the battery thermal management system based on the actual working conditions, thereby enabling the thermal management control method to be adaptively adjusted to the actual working conditions and vehicle models, avoiding overheating or insufficient heating, and achieving the best balance between power performance and economy.

[0028] 2. The thermal management control method provided by the present invention is applicable to both power batteries with electric heating configuration and power batteries with liquid heating configuration, and has the advantages of simple algorithm and strong versatility. When the power battery has a liquid heating configuration, adopting this control method is also helpful to further improve the energy utilization efficiency of the power battery, control the battery temperature difference, and enhance the battery performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the method for obtaining the heating-off threshold T C in the present invention.

[0030] Figure 2 It is a schematic diagram of the control flow of battery thermal management in the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The following describes the specific embodiments of the present invention with reference to the accompanying drawings. To fully understand the present invention, many details are described below, but for those skilled in the art, the present invention can be implemented without these details.

[0032] The present invention provides a battery thermal management control method based on operating condition optimization. The main innovation of this control method lies in: dynamically adjusting the heating-off threshold T C of the battery thermal management system based on the actual operating conditions, so that the thermal management control method can be adaptively adjusted to the actual operating conditions. The method for obtaining the heating-off threshold T C first analyzes the historical operation data, extracts the maximum discharge current value and the maximum charge current value under the actual operating conditions, and then consults the battery charge and discharge MAP table to determine the corresponding optimal heating-off threshold, so as to achieve adaptive heating control for different operating conditions and vehicle models and balance power performance and economy.

[0033] As Figure 1 shown, the method for obtaining the heating-off threshold T C of the battery thermal management system specifically includes the following steps:

[0034] S1. Obtain M maximum discharge current values I dis and M maximum charge current values I chg of the vehicle under the actual operating conditions, and store them in the I dis [M] array and the I chg [M] array respectively.

[0035] In this step, the M maximum discharge current values I dis and the M maximum charge current values I chgThe acquisition method is as follows: Sort all the discharge current values and charge current values of the vehicle during N days of operation under actual working conditions or during N charge and discharge cycles from large to small, and respectively take the first M discharge current values and the first M charge current values as the maximum discharge current value I dis and the maximum charge current value I chg and store them in the corresponding arrays. Among them, the value range of N is N≥3, and in this embodiment, it is preferably 3; the value range of M is M≥100, and in this embodiment, it is preferably 100.

[0036] S2. Based on the I dis [M] array and the I chg [M] array, obtain the maximum discharge current value I dismax and the maximum charge current value I chgmax under the corresponding working conditions.

[0037] This step first eliminates the maximum and minimum values of the elements in the I dis [M] array and the I chg [M] array, and then calculates the root mean square values of the remaining elements in the two arrays respectively to obtain the maximum discharge current value I dismax and the maximum charge current value I chgmax , and their calculation formulas are:

[0038]

[0039] In the formula: and are respectively the maximum and minimum values in the I dis [M] array, and are respectively the maximum and minimum values in the I chg [M] array.

[0040] S3. Consult the battery charge and discharge MAP table to obtain the temperature T1 corresponding to k*I dismax and the 50% SOC point, and the temperature T2 corresponding to k*I chgmax and the 50% SOC point, and take the larger value of T1 and T2 to obtain the heating off threshold T c , and its calculation formula is:

[0041] T c = max[T1, T2]

[0042] The battery charge and discharge MAP table, that is, the battery charge and discharge performance table I(SOC, T), is the factory configuration of the power battery. k represents the value coefficient, which is an empirical value, and the value range is 0.75 - 1. In this embodiment, it is preferably 0.8.

[0043] S4. Continuously execute steps S1 to S3 under actual working conditions to continuously update the heating shutdown threshold T c .

[0044] Specifically, repeat step S1, and operate for N days or N charge-discharge cycles again under actual working conditions, so as to cyclically update the I dis [M] array and I chg [M] array; then repeat steps S2 and S3 to obtain the heating shutdown threshold T based on actual working conditions c .

[0045] As Figure 2 shown, the heating configurations of existing power batteries are usually electric heating configurations (resistance heating) or liquid heating configurations (coolant heating). The working modes of the power battery management system with electric heating configurations mainly involve the shutdown mode and the heating mode, and the working modes of the power battery management system with liquid heating configurations mainly involve the shutdown mode, the heating mode, and the self-circulation mode. Then, based on different heating configurations, in order to achieve the adaptability of thermal management to actual working conditions, the battery thermal management system control method includes the following steps:

[0046] Step 10. The battery thermal management system initializes and enters the shutdown mode

[0047] Step 20. Real-time obtain the minimum temperature T min and the maximum temperature T max of the power battery, and judge whether the minimum temperature T min of the power battery is lower than the heating start threshold T0. If the judgment result is yes, execute step S30 to enter the heating mode; if the judgment result is no, further judge whether the temperature difference △T of the power battery is higher than the second temperature threshold T2 and whether the power battery is a liquid heating configuration. If both are satisfied, execute step S40 to enter the self-circulation mode, otherwise keep the shutdown mode

[0048] Specifically, the temperature difference △T of the power battery = T max - T min ; the heating start threshold T0 = the heating shutdown threshold T C - the first temperature threshold T1. Both the first temperature threshold T1 and the second temperature threshold T2 can be obtained through experiments. In this embodiment, the value range of the first temperature threshold T1 is set to 3 to 5 °C, preferably 3 °C; the value range of the second temperature threshold T2 is set to 9 to 12 °C, preferably 11 °C

[0049] Step 30. Enter the heating mode, turn on the battery heating, and real-time obtain the minimum temperature T min of the power battery, and judge whether the minimum temperature T min of the power battery is higher than the heating shutdown threshold T C, if the determination result is yes, further determine the heating configuration of the power battery. If the power battery is an electric heating configuration, enter the shutdown mode. If the power battery is a liquid heating configuration, execute step S40 to enter the self-circulation mode; if the determination result is no, maintain the heating mode.

[0050] Step S40: Enter the self-circulation mode, turn on the water pump circulation, and continuously obtain the minimum temperature T of the power battery min and the maximum temperature T max , and determine whether the minimum temperature T of the power battery min is lower than the heating start threshold T0. If the determination result is yes, enter the heating mode; if the determination result is no, further determine whether the total self-circulation duration exceeds the set duration t or whether the maximum temperature T of the power battery max is higher than the third temperature threshold T3. If so, enter the shutdown mode; otherwise, maintain the self-circulation mode.

[0051] Specifically, the value range of the set duration t is t≥20min. In this embodiment, it is preferably 20min. The third temperature threshold T3 = the battery inlet water temperature - the set temperature T4. The value range of the set temperature T4 is 3-7°C. In this embodiment, it is preferably 5°C.

[0052] According to the above steps, regardless of whether the heating configuration of the power battery is an electric heating configuration or a liquid heating configuration, this control method can dynamically adjust the battery heating strategy according to the actual working conditions, avoiding overheating or underheating, so as to achieve the best balance between power performance and economy. In addition, when the power battery is a liquid heating configuration, using this control method also helps to further improve the energy utilization efficiency of the power battery and enhance the battery performance, which is specifically reflected in the following two aspects:

[0053] (1) Introduce a pipeline waste heat utilization control method for the liquid heating configuration, that is, when exiting the heating mode, if the pipeline water temperature is much higher than the battery temperature (T min ≥T C ), turn on the self-circulation mode to utilize the pipeline waste heat, thereby improving the energy utilization efficiency; when the self-circulation exceeds a certain duration or the maximum temperature of the power battery approaches the inlet water temperature (T max ≥T3), it means that the pipeline waste heat has been fully utilized, and at this time, turn off the self-circulation to avoid unnecessary energy loss.

[0054] (2) Introduce a temperature difference self-circulation control method for the liquid heating configuration, that is, in the shutdown mode, continuously monitor the temperature difference △T of the power battery. When the temperature difference △T exceeds a certain value, turn on the self-circulation mode, thereby effectively controlling the battery temperature difference and ensuring the best performance of the battery.

[0055] The above are only the specific embodiments of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantive modification of the present invention using this concept shall fall within the scope of infringement of the protection scope of the present invention.

Claims

1. A battery thermal management control method based on operating condition optimization, characterized in that: Heating-off threshold T of the battery thermal management system C The value-taking method includes the following steps: S1. Obtain M maximum discharge current values I of the vehicle under actual working conditions dis and M maximum charge current values I chg , and store them into the I dis [M] array and the I chg [M] array respectively; S2. Based on I dis [M] array and I chg [M] array, obtain the maximum discharge current value I under the corresponding working conditions dismax and the maximum charge current value I chgmax : Where: and are respectively the maximum and minimum values in the I dis [M] array, and are respectively the maximum and minimum values in the I chg [M] array; S3. Consult the battery charge and discharge MAP table to obtain k*I dismax and the temperature T1 corresponding to the 50% SOC point and k*I chgmax and the temperature T2 corresponding to the 50% SOC point, and take the larger value of T1 and T2 to obtain the heating-off threshold T c ; where k represents the value-taking coefficient; T c = max[T1, T2] S4. Under actual working conditions, repeatedly execute steps S1 to S3 to continuously update the heating-off threshold T c .

2. The battery thermal management control method based on operating condition optimization as claimed in claim 1, wherein: In step S1, the M maximum discharge current values I dis and the M maximum charge current values I chg are obtained as follows: Sort all the discharge current values and charge current values of the vehicle during N days of operation in the actual working conditions or during N charge-discharge cycles from large to small, and respectively take the first M discharge current values and the first M charge current values as the maximum discharge current value I dis and the maximum charge current value I chg and store them in the corresponding arrays.

3. The battery thermal management control method based on operating condition optimization according to claim 2, characterized in that: The value range of N is N≥3, and the value range of M is M≥100.

4. The battery thermal management control method based on operating condition optimization as claimed in claim 1, wherein: The value range of k is 0.75 to 1.

5. A battery thermal management control method based on operating condition optimization as claimed in claim 1, characterized in that: The battery thermal management control method includes the following steps: Step 10, the battery thermal management system initializes and enters the shutdown mode; Step 20: Obtain the minimum temperature T and the maximum temperature T of the power battery in real time, and determine whether the minimum temperature T of the power battery is lower than the heating start threshold T0. If the determination result is yes, execute step S30 to enter the heating mode; if the determination result is no, further determine whether the temperature difference ΔT of the power battery is higher than the second temperature threshold T2 and whether the power battery is a liquid heating configuration. If both conditions are satisfied, execute step S40 to enter the self-circulation mode; otherwise, maintain the shutdown mode. min and the maximum temperature T max , and determine whether the minimum temperature T of the power battery min is lower than the heating start threshold T0. If the determination result is yes, execute step S30 to enter the heating mode; if the determination result is no, further determine whether the temperature difference ΔT of the power battery is higher than the second temperature threshold T2 and whether the power battery is a liquid heating configuration. If both conditions are satisfied, execute step S40 to enter the self-circulation mode; otherwise, maintain the shutdown mode; Step 30: Enter the heating mode, turn on the battery heating, and obtain the minimum temperature T of the power battery in real time min , and determine the minimum temperature T of the power battery min Is it higher than the heating-off threshold T C ? If the determination result is yes, further judge the heating configuration of the power battery. If the power battery is an electric heating configuration, enter the shutdown mode. If the power battery is a liquid heating configuration, execute step S40 to enter the self-circulation mode; If the determination result is negative, the heating mode is maintained; Step S40: Enter the self - circulation mode, turn on the water pump circulation, and obtain the minimum temperature T of the power battery in real time min and the maximum temperature T max , determine whether the minimum temperature T of the power battery min is lower than the heating start threshold T0. If the determination result is yes, enter the heating mode; if the determination result is no, further determine whether the total self - circulation duration exceeds the set duration t or whether the maximum temperature T of the power battery max is higher than the third temperature threshold T3. If so, enter the shutdown mode; otherwise, maintain the self - circulation mode.

6. The battery thermal management control method based on operating condition optimization as claimed in claim 1, wherein: The heating start threshold T0 = the heating stop threshold T C - The first temperature threshold T1, and the value range of the first temperature threshold T1 is 3 to 5 °C.

7. The battery thermal management control method based on operating condition optimization as claimed in claim 1, wherein: The value range of the second temperature threshold T2 is 9 to 12 °C.

8. The battery thermal management control method based on operating condition optimization as claimed in claim 1, wherein: The value range of the set duration t is t≥20 min.

9. The battery thermal management control method based on operating condition optimization as claimed in claim 1, wherein: The third temperature threshold T3 = the battery inlet temperature - the set temperature T4, and the value range of the set temperature T4 is 3 to 7 °C.

Images