Variable flow channel air cooling battery module cooling method based on PID control strategy and battery pack

Abstract

The invention provides a variable runner air cooling battery module cooling method based on a PID (Proportion Integration Differentiation) control strategy. The method comprises the following steps: acquiring temperature signals of all parts of a battery module through a plurality of temperature sensors and transmitting the temperature signals to a battery management system; when the battery management system calculates that delta Tmax is larger than delta TL-delta, delta Tmax is the maximum value of the temperature difference of the battery module, delta TL is a temperature difference threshold value, and the error is delta, it is judged that the temperature difference of all parts of the battery module exceeds a preset temperature difference threshold value, the position of the highest temperature Tmax of the battery module is obtained, and the position of the highest temperature Tmax of the battery module is obtained; and the control valve corresponding to the position where the highest temperature Tmax is located is controlled to be opened, and the control valves at the other air outlets are controlled to be closed, so that the runner mode is switched. The battery module can be cooled more comprehensively in multiple directions, more air can flow through the local overheating part of the battery module, heat dissipation of the local overheating part is better facilitated, and the risk that a battery is overheated is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal management of automotive power batteries, and in particular to a battery module cooling method and a battery pack with variable flow channel air cooling based on a PID control strategy. Background Art

[0002] The new energy vehicle industry is developing rapidly. As the core component of new energy vehicles, it is crucial to ensure that the power battery system works safely and efficiently. The battery module is composed of a large number of single cells. When working, it may be affected by internal and external factors such as inconsistency or working conditions, which may cause the temperature to be too high, leading to a series of problems. Accelerating the speed of chemical reactions inside the battery affects the performance of materials and even causes battery overheating and explosion. The shortened battery life, decreased energy density and reduced safety make it difficult to ensure the efficiency and safety of electric vehicles. For this reason, a corresponding thermal management system must be designed to ensure that the operating temperature of the battery module is always within a suitable range. The current mainstream thermal management technologies of air cooling and liquid cooling are inefficient, occupy a large space, and consume a lot of energy, and are no longer suitable for the development trend of future battery thermal management.

[0003] In the prior art, a Chinese invention patent application with publication number CN117039246A discloses an air-cooling partition control method for electric energy storage, including: building an air-cooling duct, the air-cooling duct includes an air-cooling system arranged above the battery pack, a fan corresponding to each battery pack located in the air inlet direction of the air-cooling system, and a fan corresponding to each battery pack in the air outlet direction, and the fan speed is set from 1 to n gears from low speed to high speed; starting the air conditioner for heating or cooling according to the temperature difference, and adjusting the fan gear according to the extreme difference, so as to control the overall temperature of the battery pack. However, it needs to set a fan corresponding to each battery pack, resulting in a large installation space and high cost. In addition, the system needs to control multiple fans, which will increase the system cost and maintenance difficulty.

[0004] The Chinese invention patent with announcement number CN105552474B discloses a circulating air-cooling heat dissipation device for power batteries, in which the control device collects the temperature values ​​on the temperature sensors at both ends of the battery, determines whether the temperature difference between the two points reaches a fixed temperature difference value, controls the opening and closing of the air inlet and outlet valves, cyclically switches the air circulation path, and realizes the circulation of air in the battery box. However, it only collects the temperature values ​​at both ends of the battery, which cannot fully reflect the temperature distribution inside the battery module, and therefore cannot more accurately control the internal temperature of the battery box. In addition, the patent controls the opening and closing of each valve so that the air flows in the flow path in the battery box in two opposite directions, realizes the cyclic switching of the cooling air direction of the battery module, and ensures that the maximum temperature and temperature difference of the battery module are within the normal range. This method can only adjust the heat dissipation speed of the battery near the air inlet, and it is difficult to regulate the temperature of the battery far away from the air inlet. And when switching the air flow direction, in order to avoid impact with the air in the opposite direction, the patent also needs to control the fan to stop for a fixed time through the battery management system, which will cause the temperature of the battery that is already too high to rise further rapidly, resulting in the risk of overheating of the battery. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems raised in the above-mentioned background technology, and provides a battery module cooling method with variable flow channel air cooling based on PID control strategy, which can cool the battery module in multiple directions and more comprehensively, and can allow more air to flow through the local overheated parts of the battery module, which is more conducive to the heat dissipation of the local overheated parts and avoids the risk of battery overheating.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A battery module cooling method with variable flow channel air cooling based on PID control strategy, comprising the following steps:

[0008] A battery pack is provided, comprising a box, a battery module, a plurality of temperature sensors and a battery management system, wherein the box comprises an outer shell and an inner shell fixed inside the outer shell, an air flow channel is arranged between the inner shell and the outer shell, the air flow channel has an air inlet and a plurality of air outlets, the air inlet is arranged at the bottom of the box, a plurality of the air outlets are arranged at intervals at the top of the box, and a control valve is arranged at each of the air outlets; the battery module is arranged in the inner shell, a plurality of the temperature sensors are connected to the inner shell at intervals, and the battery management system is electrically connected to the plurality of the temperature sensors and the control valves at each of the air outlets;

[0009] The temperature signals of various parts of the battery module are collected by using a plurality of temperature sensors and transmitted to the battery management system;

[0010] When the battery management system calculates ΔT max >ΔT L -δ, where ΔT max is the maximum temperature difference of the battery module, ΔT L is the temperature difference threshold, and the error is δ. Then it is determined that the maximum value of the temperature difference of each part of the battery module exceeds the preset temperature difference threshold, and the maximum temperature T of the battery module is obtained. max The location and control with the maximum temperature T max The control valve corresponding to the position is opened, and the control valves at the other air outlets are closed, thereby switching to the convection channel mode.

[0011] Furthermore, the air outlet includes a first air outlet, a second air outlet and a third air outlet, the first air outlet is arranged on the left side of the top of the box body, the second air outlet is arranged on the right side of the top of the box body, and the third air outlet is arranged in the middle position of the top of the box body.

[0012] Furthermore, when the maximum temperature of the battery module T max Located on the left side of the battery module, the control valve corresponding to the first air outlet is opened, and the control valves corresponding to the second air outlet and the third air outlet are closed, so that air enters from the bottom of the box and leaves from the left side of the top of the box, thereby allowing more air to flow through the left side of the battery module.

[0013] Furthermore, when the maximum temperature of the battery module T max When it is located in the middle position of the battery module, the control valve corresponding to the third air outlet is opened, and the control valves corresponding to the first air outlet and the second air outlet are closed, so that air enters from the bottom of the box and leaves from the third air outlet, thereby allowing more air to flow through the middle position of the battery module.

[0014] Furthermore, when the maximum temperature of the battery module T max Located on the right side of the battery module, the control valve corresponding to the second air outlet is opened, and the control valves corresponding to the first air outlet and the third air outlet are closed, so that air enters from the bottom of the box and leaves from the right side of the top of the box, thereby allowing more air to flow through the right side of the battery module.

[0015] Furthermore, when the temperatures at the left and right positions of the battery module are higher than the temperature at the middle position, the control valves corresponding to the first air outlet and the second air outlet are opened, and the control valve corresponding to the third air outlet is closed, so that air can flow from the left and right positions of the battery module.

[0016] Furthermore, after the flow channel mode is switched, the temperature sensor continues to collect temperature signals. If ΔT max ≤ΔT L -δ, the current flow channel mode is maintained. If ΔT max >ΔT L -δ, then continue the mode switching.

[0017] Furthermore, the battery management system sends a signal to a corresponding control valve according to a PID control algorithm, thereby controlling the operation of the corresponding control valve, thereby switching the flow channel mode.

[0018] The present invention also provides a battery pack, comprising a case, a battery module, a plurality of temperature sensors and a battery management system, wherein the case comprises an outer shell and an inner shell fixed inside the outer shell, an air flow channel is provided between the inner shell and the outer shell, the air flow channel has an air inlet and a plurality of air outlets, the air inlet is provided at the bottom of the case, a plurality of the air outlets are provided at intervals at the top of the case, and a control valve is provided at each of the air outlets; the battery module is provided in the inner shell, a plurality of the temperature sensors are connected to the inner shell at intervals, and the battery management system is electrically connected to the plurality of the temperature sensors and the control valves at each of the air outlets.

[0019] Furthermore, the battery pack also includes a heat dissipation component arranged between the inner shell and the outer shell, the heat dissipation component includes a heat conductive plate, a semiconductor refrigeration plate and a heat sink, the heat conductive plate covers the outer surface of the inner shell, the cold end of the semiconductor refrigeration plate is attached to the heat conductive plate, and the heat sink is attached to the hot end of the semiconductor refrigeration plate.

[0020] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0021] 1. In the above-mentioned variable flow channel air cooling battery module cooling method based on PID control strategy, multiple temperature sensors are provided on the inner shell of the battery pack, and the temperature of each part of the battery module can be collected through the multiple temperature sensors; when ΔT max >ΔT L -δ, it is determined that the maximum value of the temperature difference of each part of the battery module exceeds the threshold, and the highest temperature position T of the battery module is obtained. max, control the control valve corresponding to this position to open, and close the valves at other positions, so that more air flows through the position with the highest temperature, which is beneficial to the heat dissipation of the battery at this position. Therefore, the above-mentioned variable flow channel air cooling battery module cooling method based on the PID control strategy can cool the battery module in multiple directions and more comprehensively, and can concentrate the air on the local overheated part of the battery module, which is more conducive to the heat dissipation of the local overheated part and avoid the risk of overheating of the battery. At the same time, the above-mentioned variable flow channel air cooling battery module cooling method based on the PID control strategy only needs to install a fan at the air inlet. Compared with the Chinese invention patent application with publication number CN117039246A, which discloses an air-cooled partition control method for electric energy storage, it can reduce the installation area required for the battery pack, require fewer parts, reduce the weight of the entire vehicle, improve the energy efficiency of the vehicle, and have low system cost and maintenance difficulty.

[0022] 2. The cooling method of the prior art is usually passive cooling, that is, the temperature of the battery module needs to be higher than the ambient temperature before its heat dissipation component has the heat dissipation function; the battery pack used in the variable flow channel air-cooled battery module cooling method based on the PID control strategy mentioned above, the heat dissipation component includes a heat conduction plate, a semiconductor cooling plate and a heat sink, the cold end is closely attached to the heat conduction plate to absorb the heat of the battery module, and the hot end is attached to the heat sink to release heat, so that the semiconductor cooling plate continuously takes away the heat generated by the battery module during operation, actively cools the battery module, and the temperature of the cold end can be controlled within the set range, which has a better heat dissipation effect for battery modules with high heating power. At the same time, the semiconductor cooling plate and the heat sink of the heat dissipation component can adapt to different environments, and have a simple structure, few parts, and light overall weight; no refrigerant is required, it can work continuously, no pollution, no moving parts, no noise, long life, easy installation, small size and light weight, and easy maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic structural diagram of a battery pack according to a preferred embodiment of the present invention when all control valves are in a closed state;

[0024] Figure 2 for Figure 1 A schematic diagram of the structure of the battery pack shown when the control valve at the first air outlet is in an open state;

[0025] Figure 3 for Figure 1 A schematic diagram of the structure of the battery pack shown when the control valve at the third gas outlet is in an open state;

[0026] Figure 4 for Figure 1 A schematic diagram of the structure of the battery pack shown when the control valve at the second gas outlet is in an open state;

[0027] Figure 5 for Figure 1 A schematic diagram of the structure of the battery pack shown when the control valves at the first gas outlet and the second gas outlet are in an open state;

[0028] Figure 6 It is a flow chart of a battery module cooling method with variable flow channel air cooling based on PID control strategy according to a preferred embodiment of the present invention;

[0029] Main component symbols

[0030] 10. Battery pack; 11. Box body; 112. Outer shell; 113. Inner shell; 1130. Installation space; 114. Air flow channel; 115. Air inlet; 116. Air outlet; 117. First air outlet; 118. Second air outlet; 119. Third air outlet; 12. Control valve; 13. Battery module; 15. Temperature sensor; 17. Heat dissipation assembly; 171. Heat conduction plate; 172. Semiconductor cooling sheet; 173. Heat sink. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may be a component centered thereon. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may be a component centered thereon. When a component is considered to be "set on" another component, it may be directly set on the other component or there may be a component centered thereon. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0034] Please also see Figures 1 to 6 A preferred embodiment of the present invention provides a battery module cooling method with variable flow channel air cooling based on a PID control strategy, comprising the following steps:

[0035] S1, providing a battery pack 10, the battery pack 10 includes a box 11, a battery module 13, a plurality of temperature sensors 15 and a battery management system (BMS system, not shown).

[0036] The housing 11 includes an outer shell 112 and an inner shell 113 fixed in the outer shell 112, and an air flow channel 114 is provided between the inner shell 113 and the outer shell 112. In the present embodiment, the outer shell 112 and the inner shell 113 are both roughly rectangular, and the air flow channel 114 is arranged around the outer periphery of the inner shell 113. The air flow channel 114 has an air inlet 115 and a plurality of air outlets 116, and the air inlet 115 and the plurality of air outlets 116 all pass through the outer shell 112 of the housing 11 to communicate with the air flow channel 114. The air inlet 115 is provided at the bottom of the housing 11, and a fan (not shown) may be provided at the air inlet 115 to introduce air into the air flow channel 114 through the air inlet 115. A plurality of air outlets 116 are arranged at intervals at the top of the housing 11, and a control valve 12 for controlling the opening and closing of the corresponding air outlet 116 is provided at each air outlet 116. In this embodiment, the air outlet 116 includes a first air outlet 117, a second air outlet 118 and a third air outlet 119. The first air outlet 117 is arranged on the left side of the top of the box body 11, the second air outlet 118 is arranged on the right side of the top of the box body 11, and the third air outlet 119 is arranged in the middle position of the top of the box body 11. The first air outlet 117, the second air outlet 118 and the third air outlet 119 are all provided with a control valve 12.

[0037] The inner shell 113 is surrounded by an installation space 1130 for installing the battery module 13. The battery module 13 is arranged in the installation space 1130 of the inner shell 113. In this embodiment, the battery module 13 includes 9 single cells of the power battery, the mass of the battery module 13 accounts for about 20% of the weight of the whole vehicle system, and the mass of the box 11 accounts for about 10% of the total weight of the battery pack. It can be understood that in other embodiments, the number of single cells, the weight of the battery module 13 and the weight of the box 11 can be set to other values ​​as needed, and the present invention is not limited thereto.

[0038] The battery pack 10 also includes a heat dissipation assembly 17 disposed between the inner shell 113 and the outer shell 112. In this embodiment, the heat dissipation assembly 17 includes a heat conducting plate 171, a semiconductor cooling sheet 172 and a heat sink 173. The heat conducting plate 171 covers the outer surface of the inner shell 113; the cold end of the semiconductor cooling sheet 172 is attached to the side of the heat conducting plate 171 away from the inner shell 113; and the heat sink 173 is attached to the hot end of the semiconductor cooling sheet 172. The material of the heat conducting plate 171 in this embodiment is an aluminum silicon alloy, which has a low density and a good thermal conductivity. The function of the heat conducting plate 171 is to receive the heat emitted by the battery module 13 when it is working, avoiding direct contact between the semiconductor cooling sheet 172 and the inner shell 113 while ensuring timely heat transfer.

[0039] The current passing through the semiconductor refrigeration sheet 172 should be between 10mA and 100mA, and the voltage across the two ends should not exceed 15V, which should be adjusted according to different application scenarios. Thermal conductivity is an important parameter for measuring the cooling effect of the semiconductor refrigeration sheet 172. In this embodiment, the thermal conductivity should be between 10W and 50W. The maximum temperature difference is an indicator for measuring the cooling capacity of the semiconductor refrigeration sheet 172. In this embodiment, the temperature difference range should be between -50°C and 70°C. The heat sink 173 is made of aluminum silicon alloy, which has high thermal conductivity.

[0040] A plurality of temperature sensors 15 are installed at intervals on the outer surface of the inner shell 113 to monitor the temperature of the battery pack around, at the top and at the bottom in real time. In this embodiment, the temperature sensor 15 is installed on the outside of the heat sink 173 and connected to the outer surface of the inner shell 113 through the heat sink 173. The plurality of temperature sensors 15 are respectively arranged at the surrounding, middle top and middle bottom positions of the battery module 13. The temperature sensor 15 of this embodiment is a thermistor sensor, which has high sensitivity and a large operating temperature range.

[0041] The battery management system is electrically connected to the multiple temperature sensors 15 and the control valves 12 at each gas outlet 116. This embodiment adopts the battery management system of the prior art, which is not described here for the sake of space. In this embodiment, the battery management system sends a signal to the corresponding control valve 12 according to the PID control algorithm, thereby controlling the switch of the control valve 12.

[0042] S2, collecting temperature signals of various parts of the battery module 13 through multiple temperature sensors 15 and transmitting them to the battery management system.

[0043] S3, within the preset time period, when the battery management system calculates ΔT max >ΔT L -δ, where ΔT max is the maximum value of the temperature difference of the battery module 13, ΔT Lis the set temperature difference threshold, the error is δ, then it is determined that the maximum value of the temperature difference of each part of the battery module 13 exceeds the set temperature difference threshold, and the maximum temperature T of the battery module 13 is obtained. max The location and control of the maximum temperature T max The control valve 12 corresponding to the position is opened, and the control valves 12 at the other gas outlets 116 are closed to switch the flow channel mode.

[0044] Specifically, in this embodiment, ΔT max The temperature sensor 15 collects the temperature signals of various parts of the battery pack 10, and then calculates the temperature difference between the various parts through the collected temperature signals, and finally takes the maximum value from the temperature difference values, which is ΔT max . T max The temperature sensor 15 is used to collect the temperature signals of various parts of the battery pack 10, and the maximum temperature is taken as ΔT max When T max Located on the left side of the battery module 13, the control valve 12 corresponding to the first air outlet 117 is opened, and the control valves 12 corresponding to the second air outlet 118 and the third air outlet 119 are closed, so that air enters from the bottom of the box body 11 and leaves from the left side of the top of the box body 11, so that more air flows through the left side of the battery module 13, which is more conducive to heat dissipation. max When the battery module 13 is in the middle, the control valve 12 corresponding to the third air outlet 119 is opened, and the control valves 12 corresponding to the first air outlet 117 and the second air outlet 118 are closed, so that air enters from the bottom of the box 11 and leaves from the third air outlet 119, so that more air flows through the middle position of the top of the box 11, which is more conducive to cooling the battery module 13 in the middle. max Located on the right side of the battery module 13, the control valve 12 corresponding to the second air outlet 118 is opened, and the control valves 12 corresponding to the first air outlet 117 and the third air outlet 119 are closed, so that air enters from the bottom of the box body 11 and leaves from the right side of the top of the box body 11, so that more air flows through the right side of the battery module 13, which is more conducive to heat dissipation. In addition, when the temperature of the left and right positions of the battery module 13 is higher than the temperature of the middle position, the control valves 12 corresponding to the first air outlet 117 and the second air outlet 118 are opened, and the control valve 12 corresponding to the third air outlet 118 is closed, so that more air flows from the left and right positions of the battery module 13 to take away heat.

[0045] After the flow channel mode is switched, the temperature sensor 15 continues to collect temperature signals. If ΔT max ≤ΔT L -δ, the current flow channel mode is maintained. If ΔT max >ΔTL -δ, then continue mode switching.

[0046] In the above-mentioned variable flow channel air cooling method for the battery module 13 based on the PID control strategy, a plurality of temperature sensors 15 are provided on the inner shell 113 of the battery pack 10, and the temperature of each part of the battery module 13 can be collected by the plurality of temperature sensors 15; when ΔT max >ΔT L -δ, it is determined that the maximum value of the temperature difference of each part of the battery pack exceeds the set temperature difference threshold, and the highest temperature position T of the battery pack 10 is obtained. max , control the control valve 12 corresponding to the position to open, and close the valves at other positions, so that air flows through the position with the highest temperature, thereby facilitating the heat dissipation of the battery at this position. Therefore, the above-mentioned variable flow channel air-cooled battery module 13 cooling method based on the PID control strategy can cool the battery module 13 in multiple directions and more comprehensively, and can concentrate the air on the local overheated part of the battery module 13, which is more conducive to the heat dissipation of the local overheated part and avoids the risk of overheating of the battery. At the same time, the above-mentioned variable flow channel air-cooled battery module 13 cooling method based on the PID control strategy only needs to install a fan at the air inlet. Compared with the Chinese invention patent application with publication number CN117039246A, which discloses an air-cooled partition control method for electric energy storage, it can reduce the installation area required for the battery pack 10, requires fewer parts, can reduce the weight of the entire vehicle, improve the energy efficiency of the vehicle, and has low system cost and maintenance difficulty.

[0047] The cooling method of the prior art is usually passive cooling, that is, the temperature of the battery module 13 needs to be higher than the ambient temperature before its heat dissipation component 17 has a heat dissipation function; the battery pack 10 used in the variable flow channel air-cooled battery module 13 cooling method based on the PID control strategy, the heat dissipation component 17 includes a heat conducting plate 171, a semiconductor cooling plate 172 and a heat sink 173, the cold end is closely attached to the heat conducting plate 171, absorbing the heat of the battery module 13, and the hot end is attached to the heat sink 173, releasing heat, so that the semiconductor cooling plate 172 continuously takes away the heat generated by the battery module 13, actively cools the battery module 13, and the temperature of the cold end can be controlled within a set range, and the heat dissipation effect is better for the battery module 13 with high heating power. At the same time, the semiconductor cooling plate 172 and the heat sink 173 of the heat dissipation component 17 can adapt to different environments, and have a simple structure, few parts, and light overall weight; no refrigerant is required, it can work continuously, no pollution, no moving parts, no noise, long life, easy installation, small size and light weight, and easy maintenance.

[0048] The above description is a detailed description of the preferred feasible embodiments of the present invention, but the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modified changes completed under the technical spirit suggested by the present invention should fall within the patent scope covered by the present invention.

Claims

1. A battery module cooling method with variable flow channel air cooling based on PID control strategy, characterized in that: The following steps are involved: A battery pack is provided, comprising a box, a battery module, a plurality of temperature sensors and a battery management system, wherein the box comprises an outer shell and an inner shell fixed inside the outer shell, an air flow channel is arranged between the inner shell and the outer shell, the air flow channel has an air inlet and a plurality of air outlets, the air inlet is arranged at the bottom of the box, a plurality of the air outlets are arranged at intervals at the top of the box, and a control valve is arranged at each of the air outlets; the battery module is arranged in the inner shell, a plurality of the temperature sensors are connected to the inner shell at intervals, and the battery management system is electrically connected to the plurality of the temperature sensors and the control valves at each of the air outlets; The temperature signals of various parts of the battery module are collected by using a plurality of temperature sensors and transmitted to the battery management system; When the battery management system calculates ΔT max >ΔT L -δ, where ΔT max is the maximum temperature difference of the battery module, ΔT L is the temperature difference threshold, and the error is δ. Then it is determined that the maximum value of the temperature difference of each part of the battery module exceeds the preset temperature difference threshold, and the maximum temperature T of the battery module is obtained. max The location and control with the maximum temperature T max The control valve corresponding to the position is opened, and the control valves at the other air outlets are closed, thereby switching to the convection channel mode.

2. The battery module cooling method with variable flow channel air cooling based on PID control strategy according to claim 1, characterized in that: The air outlet includes a first air outlet, a second air outlet and a third air outlet, the first air outlet is arranged on the left side of the top of the box body, the second air outlet is arranged on the right side of the top of the box body, and the third air outlet is arranged in the middle position of the top of the box body.

3. The battery module cooling method with variable flow channel air cooling based on PID control strategy as claimed in claim 2, characterized in that: When the maximum temperature of the battery module T max Located on the left side of the battery module, the control valve corresponding to the first air outlet is opened, and the control valves corresponding to the second air outlet and the third air outlet are closed, so that air enters from the bottom of the box and leaves from the left side of the top of the box, thereby allowing more air to flow through the left side of the battery module.

4. The battery module cooling method with variable flow channel air cooling based on PID control strategy as claimed in claim 2, characterized in that: When the maximum temperature of the battery module T max When it is located in the middle position of the battery module, the control valve corresponding to the third air outlet is opened, and the control valves corresponding to the first air outlet and the second air outlet are closed, so that air enters from the bottom of the box and leaves from the third air outlet, thereby allowing more air to flow through the middle position of the battery module.

5. The battery module cooling method with variable flow channel air cooling based on PID control strategy according to claim 2, characterized in that: When the maximum temperature of the battery module T max Located on the right side of the battery module, the control valve corresponding to the second air outlet is opened, and the control valves corresponding to the first air outlet and the third air outlet are closed, so that air enters from the bottom of the box and leaves from the right side of the top of the box, thereby allowing more air to flow through the right side of the battery module.

6. The battery module cooling method with variable flow channel air cooling based on PID control strategy as claimed in claim 2, characterized in that: When the temperatures at the left and right positions of the battery module are higher than the temperature at the middle position, the control valves corresponding to the first and second air outlets are opened, and the control valve corresponding to the third air outlet is closed, so that air can flow from the left and right positions of the battery module.

7. The battery module cooling method with variable flow channel air cooling based on PID control strategy as claimed in claim 2, characterized in that: After the flow channel mode is switched, the temperature sensor continues to collect temperature signals. If ΔT max ≤ΔT L -δ, the current flow channel mode is maintained. If ΔT max >ΔT L -δ, then continue mode switching.

8. The battery module cooling method with variable flow channel air cooling based on PID control strategy as claimed in claim 2, characterized in that: The battery management system sends a signal to the corresponding control valve according to the PID control algorithm, thereby controlling the operation of the corresponding control valve, thereby switching the flow channel mode.

9. A battery pack, characterized in that: It includes a box body, a battery module, multiple temperature sensors and a battery management system. The box body includes an outer shell and an inner shell fixed inside the outer shell. An air flow channel is provided between the inner shell and the outer shell. The air flow channel has an air inlet and a plurality of air outlets. The air inlet is provided at the bottom of the box body, and a plurality of air outlets are provided at intervals at the top of the box body. A control valve is provided at each air outlet. The battery module is provided in the inner shell, and a plurality of temperature sensors are connected to the inner shell at intervals. The battery management system is electrically connected to the plurality of temperature sensors and the control valves at each of the air outlets.

10. The battery pack according to claim 9, characterized in that: The battery pack also includes a heat dissipation component arranged between the inner shell and the outer shell, and the heat dissipation component includes a heat conduction plate, a semiconductor refrigeration plate and a heat sink. The heat conduction plate covers the outer surface of the inner shell, the cold end of the semiconductor refrigeration plate is attached to the heat conduction plate, and the heat sink is attached to the hot end of the semiconductor refrigeration plate.

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