Battery pack thermal management method, storage medium and battery pack controller

Abstract

The invention relates to a battery pack heat management method, a storage medium and a battery pack controller. The battery pack is mounted on electric equipment, the battery pack comprises a liquid cooling plate, and a heat exchange medium in the liquid cooling plate can be driven by a water pump to circularly flow; the thermal management method is applied to the situation that the electric equipment is in a power-off state. The method comprises the steps that the temperature difference between the highest temperature and the lowest temperature of a battery cell in a battery pack is obtained; and according to the temperature difference, whether the water pump is started or not is controlled. According to the working condition that the electric equipment is in a low-temperature environment and is powered off, when the battery management system detects that the battery temperature difference is large, the water pump is started to rotate, the heat exchange medium with the preset flow is used for equalizing the temperature of the battery pack, and high-temperature energy of the middle battery cells is transferred to the low-temperature edge battery cells, so that the lowest temperature of the battery pack is increased, and the temperature difference is reduced; the low-temperature endurance mileage and the dynamic property of the battery pack are improved, and the service life of the battery pack is prolonged.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a battery pack thermal management method, a storage medium and a battery pack controller. Background Art

[0002] At present, the activity of lithium ions decreases at low temperatures, resulting in a weakened battery discharge capacity, which leads to a significant reduction in the power and endurance of electric vehicles compared to normal temperatures. Under normal working conditions, the coolant circulates in the liquid cold plate driven by a water pump to manage the heat of the battery cells, so the overall temperature of the battery pack is relatively balanced. In low temperature environments, the vehicle can heat the coolant through a heater to heat the battery cells in the battery pack to improve battery performance.

[0003] However, when the vehicle is in a low-temperature environment and is in a power-off state, for example, the vehicle is parked in a low-temperature environment, the edge cells in the battery pack will dissipate heat faster and thus the temperature will drop faster, resulting in a large temperature difference between the edge cells and the middle cells of the battery pack. This temperature difference will cause the battery pack cell performance to deteriorate and affect the service life of the battery pack.

[0004] In the related art, the low temperature area of ​​the battery pack is heated only when the vehicle is powered on or ready to be powered on, and the control logic is relatively complex. Currently, there is no technology for thermal management of the battery pack when the vehicle is completely powered off. Summary of the invention

[0005] The present application provides a battery pack thermal management method, a storage medium and a battery pack controller to solve or at least improve the problems in the above-mentioned background technology, so that under low temperature conditions, the overall temperature difference of the battery pack is reduced, the low-temperature endurance and power of the battery pack are improved, and the service life is extended.

[0006] On one hand, the present application provides a battery pack thermal management method, wherein the battery pack is installed on an electrical device, the battery pack includes a liquid cooling plate, and the heat exchange medium in the liquid cooling plate can be driven by a water pump to circulate; the thermal management method is applied to the electrical device when it is in a power-off state, the method comprising: obtaining the temperature difference between the highest temperature and the lowest temperature of the battery cells in the battery pack; and controlling whether to turn on the water pump based on the temperature difference.

[0007] In the working condition where the electrical equipment is in a low-temperature environment and powered off, when the battery management system detects a large temperature difference in the battery, the water pump is turned on to equalize the temperature of the battery pack with a heat exchange medium at a preset flow rate. The high-temperature energy of the middle battery cells is transferred to the low-temperature edge battery cells, so that the lowest temperature of the battery pack is increased, the temperature difference is reduced, the low-temperature cruising range and power performance of the battery pack are improved, and the service life of the battery pack is extended. Since only the water pump is rotated to generate a heat exchange medium with a preset flow rate, and components such as heaters do not need to work, only a very small amount of electricity is consumed, which has basically no impact on the overall cruising range of the battery pack. At the same time, since the water pump generates a certain amount of heat during operation, it slightly heats the heat exchange medium, further improving the temperature increase and equalization effect.

[0008] Further, the step of controlling whether to turn on the water pump according to the temperature difference includes: when the temperature difference is greater than or equal to a first threshold, turning on the water pump to circulate the heat exchange medium at a preset flow rate.

[0009] Further, the first threshold is taken from the range of [3, 12].

[0010] Further, turning on the water pump to circulate the heat exchange medium at a preset flow rate includes: the water pump circulates the heat exchange medium at a first flow rate for a first duration and then circulates at a second flow rate; wherein the first flow rate is greater than the second flow rate.

[0011] Further, after the step of turning on the water pump to circulate the heat exchange medium at a preset flow rate when the temperature difference is greater than or equal to the first threshold, the following steps are also included: when the temperature difference is less than or equal to a second threshold, or when the opening duration of the water pump reaches a preset duration, turning off the water pump.

[0012] Further, the second threshold is taken from the range of [1, 10], and the second threshold is at least 2 less than the first threshold; the preset duration is from 1 hour to 6 hours.

[0013] Further, a plurality of liquid cooling plates are provided, and the liquid cooling plates are arranged between adjacent battery cells.

[0014] Further, the battery cell includes a first side surface, and the first side surface is disposed opposite to the liquid cooling plate; wherein the first side surface is the surface with the largest surface area among the surfaces of the battery cell.

[0015] The present application also provides a computer-readable storage medium, on which a battery pack thermal management program is stored. When the thermal management program is executed, the battery pack thermal management method described in any one of the above technical solutions is implemented.

[0016] Finally, the present application also provides a battery pack controller, including: a memory, a processor, and a battery pack thermal management program stored in the memory and capable of running on the processor; when the processor executes the battery pack thermal management program, it implements the battery pack thermal management method described in any of the above technical solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the battery pack of an embodiment of the present application.

[0018] Figure 2 It is a schematic diagram of a battery pack thermal management system according to an embodiment of the present application.

[0019] Figure 3 It is a flow chart of the battery pack thermal management method according to an embodiment of the present application. DETAILED DESCRIPTION

[0020] Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention, so the present invention is not limited to the specific implementation disclosed below.

[0021] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, inside, outside, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0022] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0023] In the description of the present invention, reference to terms such as "one embodiment", "some embodiments", "illustrative embodiment", "example", "specific example", or "some implementation methods" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention.

[0024] See also Figure 1, this embodiment provides a battery pack 100 for installation on a vehicle to provide power for the vehicle. The battery pack 100 includes a plurality of battery packs arranged side by side along a first direction X, each battery pack includes a plurality of battery cells 110 arranged along a second direction Y, and the battery cells 110 are connected in series or in parallel to form an electrical connection circuit of the entire battery pack. The battery pack 100 also includes a plurality of liquid cooling plates 120. Exemplarily, the liquid cooling plates 120 extend along the second direction Y and are arranged between adjacent battery packs. The liquid cooling plates 120 have a flow channel for the flow of a heat exchange medium. A liquid inlet pipe and a liquid outlet pipe (not shown) are connected to the liquid cooling plate 120, so that the heat exchange medium flows into the liquid cooling plate 120 through the liquid inlet pipe, performs heat exchange with the battery cells 110 in the battery pack, and then flows out from the liquid outlet pipe. The connection method of the liquid inlet pipe and the liquid outlet pipe to the liquid cooling plate 120 can be set according to the specific situation. The liquid cooling plates 120 can be connected in series or in parallel. The series connection means that the heat exchange medium flows through each liquid cooling plate in sequence, and the parallel connection means that the heat exchange medium flows through each liquid cooling plate at the same time. The prior art can be referred to and will not be described in detail here. In addition, the battery pack 100 also includes a box body 140, an upper cover 130 and a bottom plate 150, thereby forming a accommodating space. It can be understood that the liquid cooling plate 120 can be arranged between every two adjacent battery groups, or the liquid cooling plate 120 can be arranged between some adjacent battery groups, and foam can be arranged between another part of adjacent battery groups to play a role in heat insulation and absorbing the expansion of the battery cells. This embodiment does not make specific limitations on this.

[0025] The battery cell 110 may be a soft pack battery cell, a square shell battery cell or a blade battery cell. The battery cell 110 has multiple surfaces. In this embodiment, the liquid cooling plate 120 is opposite to the surface with the largest surface area among the surfaces of the battery cell 110, thereby improving the heat exchange efficiency. Exemplarily, the liquid cooling plate 120 is in heat transfer contact with the largest surface of the battery cell, for example, directly in contact or through a thermally conductive adhesive.

[0026] See also Figure 2 , which is a schematic diagram of the thermal management system of the battery pack. The battery pack includes a liquid inlet and a liquid outlet. The liquid inlet is connected to the liquid inlet pipe of the battery pack, and the liquid outlet is connected to the liquid outlet pipe of the battery pack. When the system is in working state, for example, when the vehicle is in the state of power-on driving, the water pump in the thermal management system works to drive the heat exchange medium to flow. The heat exchange medium enters the battery pack from the liquid inlet, flows in the liquid cooling plate to exchange heat with the battery cell, and then flows out from the liquid outlet. After being heated by the heater or cooled by the refrigeration system, it enters the liquid cooling plate of the battery pack again, exchanges heat with the battery cell, and then flows out. This cycle flows to keep the battery cell working at a suitable temperature.

[0027] Specifically, when the temperature of the battery cell is too high, the heat exchange medium passes through the loop of the refrigeration system, and the refrigeration system cools the heat exchange medium, so that the heat exchange medium cools the battery cell; when the temperature of the battery cell is too low, the heat exchange medium passes through the loop of the heater, and the heater heats the heat exchange medium, so that the heat exchange medium heats the battery cell.

[0028] In the prior art, when the vehicle is powered off, the battery pack thermal management system stops working, and accordingly, the water pump also stops running.

[0029] Due to the different positions of the cells in the battery pack, the degree and efficiency of heat dissipation to the outside are also different. For the cells at the edge of the battery pack, since they are close to the frame of the box and other structures, they are more likely to exchange heat with the outside world than the cells in the middle of the battery pack. Therefore, when the vehicle is powered off, the battery pack thermal management system stops working. When the vehicle is parked in a low temperature environment, the cells at the edge of the battery pack dissipate heat faster than the cells in the middle, resulting in a lower temperature for the edge cells than for the middle cells. It can be understood that when the vehicle is powered off, this temperature difference will gradually increase, and as the power-off time continues to increase, the overall temperature of the battery pack will eventually converge with the external ambient temperature, so the above temperature difference will gradually decrease and eventually approach zero. However, if the user starts the vehicle again when the temperature difference is large, this temperature difference will cause the battery capacity and power to drop rapidly, and using the battery under uneven temperature for a long time will seriously affect the life of the battery pack.

[0030] In addition, since the liquid cooling system of this embodiment is in the form of multiple liquid cooling plates arranged between adjacent battery cells, and the multiple liquid cooling plates are relatively independent, they cannot play the role of equalizing the temperature of the entire battery pack, that is, under low-power conditions, the multiple independent liquid cooling plates cannot directly transfer the high-temperature heat of the middle battery cell to the edge battery cell. This design of the liquid cooling system further increases the problem of uneven temperature between the edge battery cells and the middle battery cell.

[0031] See also Figure 3 This application proposes a battery pack thermal management method based on a vehicle in a low-temperature environment and in a power-off condition. The method includes: obtaining the temperature difference between the highest temperature and the lowest temperature of the battery cells in the battery pack; and controlling whether to turn on the water pump based on the temperature difference.

[0032] It can be understood that, illustratively, when the vehicle is in a low-temperature electrical condition, the middle battery cell usually has the highest temperature, while the edge battery cell has the lowest temperature. When the temperature difference is too large, if the user uses the vehicle again at this time, it will affect the performance of the battery cell. Therefore, in this embodiment, when the temperature difference between the highest temperature and the lowest temperature is greater than or equal to the threshold, the water pump in the thermal management system is turned on, that is, when the temperature difference is greater than or equal to the threshold, the water pump is operated, so that the heat exchange medium in the liquid cold plate circulates through the operation of the water pump. After multiple cycles, the high-temperature energy of the middle battery cell is transferred to the low-temperature edge battery cell, so that the minimum temperature of the battery pack is increased, the temperature difference is reduced, the low-temperature cruising range and power of the battery pack are improved, and the service life of the battery pack is extended. In the above process, only the water pump is started, and there is no need to turn on the heater. On the contrary, when there is only a small temperature difference and the threshold is not reached, the water pump will not be started.

[0033] In addition, since the water pump itself will generate a certain amount of heat during operation, it has a slight heating effect on the heat exchange medium, further improving the temperature rise and temperature equalization effect.

[0034] It should be noted that the above detection, acquisition and control tasks can be implemented by the battery management system BMS (Battery Management System) of the battery pack.

[0035] Specifically, the step of controlling whether to start the water pump according to the temperature difference includes: when the temperature difference is greater than or equal to a first threshold, starting the water pump to allow the heat exchange medium to circulate at a preset flow rate.

[0036] Exemplarily, the first threshold is taken from the range of [3, 12], expressed in degrees Celsius. In an optional embodiment, the first threshold is 10, that is, when it is detected that the temperature difference between the highest temperature and the lowest temperature of the battery cell in the battery pack is greater than or equal to 10°C, the water pump is turned on.

[0037] Further, in the present embodiment, starting the water pump to circulate the heat exchange medium at a preset flow rate includes: the water pump circulates the heat exchange medium at a first flow rate for a first duration, and then circulates at a second flow rate; wherein the first flow rate is greater than the second flow rate. In other words, the temperature difference of the battery pack is first quickly reduced by a larger flow rate, and then circulated at a smaller flow rate to further reduce the temperature difference. This method can reduce the power consumed by the operation of the water pump, reduce the impact on the battery pack's cruising range, and quickly achieve temperature uniformity. Exemplarily, the first flow rate is 10L / min to 25L / min, the first duration is 1min to 10min, and the second flow rate is 3L / min to 5L / min. In a specific embodiment, the water pump circulates the heat exchange medium at a flow rate of 20L / min for 2min, and then circulates at a flow rate of 4L / min, until the temperature difference is reduced to within the second threshold, or the water pump runs for a predetermined duration, which will be described below.

[0038] Of course, it is understandable that turning on the water pump to circulate the heat exchange medium at a preset flow rate can also mean: the water pump circulates the heat exchange medium at a first flow rate for a first duration, then at a second flow rate for a second duration, then at a third flow rate for a third duration, or further includes: then circulates at a fourth flow rate, etc., wherein the first flow rate> the second flow rate> the third flow rate> the fourth flow rate. The duration and flow rate of each stage can be set according to the specific battery pack and the use environment, as long as the water pump circulates the heat exchange medium at a larger flow rate in the initial operation stage, and then at a smaller flow rate, which does not deviate from the essence of this application.

[0039] In addition, in some other embodiments, the preset flow rate may also be a fixed flow rate, such as a smaller flow rate, exemplarily 5 L / min, which does not deviate from the essence of the present application.

[0040] Furthermore, when the water pump is turned on, after multiple cycles of the heat exchange medium, the high temperature energy of the middle battery cell is transferred to the low temperature edge battery cell, so that the minimum temperature of the battery pack is increased and the temperature difference is gradually reduced; when the temperature difference is less than or equal to the second threshold, the water pump is turned off. It can be understood that turning off the water pump includes executing the water pump from on to off, or keeping the water pump off.

[0041] Exemplarily, the second threshold is taken from the range of [1, 10], and the second threshold is at least 2 less than the first threshold, expressed in degrees Celsius. For example, the second threshold is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, etc.; and the second threshold is set to be at least 2 less than the first threshold to ensure that the temperature difference can be reduced by at least 2°C, for example, the second threshold is 2°C, 3°C, 4°C, 5°C, 6°C, etc. less than the first threshold, so as to ensure the effect of improving the performance and service life of the battery cell.

[0042] In an optional embodiment, the first threshold value is 10 and the second threshold value is 6, that is, when it is detected that the temperature difference between the highest temperature and the lowest temperature of the battery cell is greater than or equal to 10°C, the water pump is turned on; after the water pump has run for a period of time and the temperature difference between the highest temperature and the lowest temperature of the battery cell is less than or equal to 6°C, the water pump is turned off.

[0043] In addition, considering the variability of the external environment or other unexpected factors, such as the failure of the temperature sensor resulting in temperature detection deviation, in order to ensure that the water pump can work in a controllable manner, when the water pump is turned on for a predetermined time, the water pump is turned off. Exemplarily, the predetermined time is taken from the range of 1 hour to 6 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, 5 hours or 6 hours. In an optional embodiment, the predetermined time is 5 hours, that is, even if the temperature difference between the highest temperature and the lowest temperature of the battery cell is not less than or equal to the second threshold, the water pump is turned off when the water pump is turned on for 5 hours. Therefore, when the temperature difference between the highest temperature and the lowest temperature of the battery cell is not less than or equal to the second threshold, it will be further detected whether the water pump is turned on for a predetermined time. In this way, even due to the variability of the external environment or other unexpected factors, the water pump can be turned off after the predetermined working time, ensuring the controllability of the power used by the water pump, thereby ensuring the battery pack's range. In a specific embodiment, when the water pump rotates at a low speed to generate a flow rate of 4L / min and works continuously for 5 hours, the electricity it consumes is less than 0.2kWh, so it has little effect on the battery life of the battery pack.

[0044] It is understandable that, although the liquid cooling plate is disposed between adjacent battery cells in the above embodiment, the battery pack thermal management method of the present application is also applicable to the case where the liquid cooling plate is disposed above or below the battery cell, which does not deviate from the essence of the present application. In addition, the battery pack thermal management method of the present application is also applicable to other electrical equipment, such as electric aircraft, electric trains, electric ships, etc.

[0045] In addition, the present application also provides a computer-readable storage medium, on which a battery pack thermal management program is stored. When the thermal management program is executed, the above-mentioned battery pack thermal management method is implemented.

[0046] Finally, the present application also provides a battery pack controller, comprising: a memory, a processor, and a battery pack thermal management program stored in the memory and executable on the processor; when the processor executes the battery pack thermal management program, the above-mentioned battery pack thermal management method is implemented.

[0047] It should be noted that although the present invention is disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any technical personnel in this field may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined by the claims of the present invention.

Claims

1. A method for thermal management of a battery pack, wherein the battery pack is installed on an electrical device, the battery pack comprises a liquid cooling plate, and a heat exchange medium in the liquid cooling plate can be driven by a water pump to circulate; The thermal management method is applied to the power-consuming device when the power-consuming device is in a power-off state, and the method includes: Obtaining the temperature difference between the highest temperature and the lowest temperature of the battery cells in the battery pack; According to the temperature difference, whether to start the water pump is controlled.

2. The battery pack thermal management method according to claim 1, It is characterized in that The step of controlling whether to start the water pump according to the temperature difference includes: when the temperature difference is greater than or equal to a first threshold, starting the water pump to allow the heat exchange medium to circulate at a preset flow rate.

3. The battery pack thermal management method according to claim 2, It is characterized in that The first threshold is taken from the range of [3,12].

4. The battery pack thermal management method according to claim 2, It is characterized in that Turning on the water pump to circulate the heat exchange medium at a preset flow rate includes: the water pump causes the heat exchange medium to circulate at a first flow rate for a first time period, and then circulate at a second flow rate; wherein the first flow rate is greater than the second flow rate.

5. The battery pack thermal management method according to claim 2, It is characterized in that When the temperature difference is greater than or equal to a first threshold, the step of starting the water pump to circulate the heat exchange medium at a preset flow rate also includes: when the temperature difference is less than or equal to a second threshold, or when the water pump is turned on for a predetermined time, turning off the water pump.

6. The battery pack thermal management method according to claim 5, It is characterized in that The second threshold is taken from the range of [1,10], and the second threshold is at least 2 less than the first threshold; The predetermined duration is 1 hour to 6 hours.

7. The battery pack thermal management method according to any one of claims 1 to 6, It is characterized in that A plurality of liquid cooling plates are provided, and the liquid cooling plates are arranged between adjacent battery cells.

8. The battery pack thermal management method according to claim 7, It is characterized in that The battery cell includes a first side surface, and the first side surface is arranged opposite to the liquid cooling plate; wherein the first side surface is the surface with the largest surface area among all surfaces of the battery cell.

9. A computer-readable storage medium, It is characterized in that The computer-readable storage medium stores a battery pack thermal management program, and when the thermal management program is executed, the battery pack thermal management method according to any one of claims 1 to 8 is implemented.

10. A battery pack controller, It is characterized in that include: A memory, a processor, and a battery pack thermal management program stored in the memory and executable on the processor; When the processor executes the battery pack thermal management program, it implements the battery pack thermal management method as described in any one of claims 1-8.

Images