Battery pack cooling system

Abstract

The invention relates to a cooling system used in battery packs in the field of energy storage systems, which, by means of intermediate cooling plates (20) placed between the battery cells (10), achieves homogeneous temperature distribution and minimum temperature difference in 5 the battery packs, and at the same time increases the performance and efficiency of the battery packs, maximizing their operational life and reliability.

Description

[0001] DESCRIPTION

[0002] BATTERY PACK COOLING SYSTEM

[0003] Technical Field

[0004] The invention relates to a cooling system used in battery packs in the field of energy storage systems.

[0005] In particular, the invention relates to a cooling system which, by means of intermediate cooling plates placed between the battery cells, achieves homogeneous temperature distribution and minimum temperature difference in the battery packs, and at the same time increases the performance and efficiency of the battery packs, maximizing their operational life and reliability.

[0006] State of the Art

[0007] Nowadays, the shift towards renewable energy sources instead of environmentally damaging energy sources has increased and energy storage systems have become an important part of sustainable energy solutions.

[0008] Battery packs used in the field of energy storage systems are created by combining batteries, which are electrochemical devices that store energy produced from different sources. In an energy storage system, multiple battery cells are brought together to form a battery pack. These battery packs are specially designed to perform the functions of storing and supplying energy, while also ensuring that the battery cells operate safely and efficiently. Battery cells are electrically interconnected and can be arranged in series or parallel to meet desired voltage and capacity requirements. Such arrangements optimize the energy storage capacity of the system while also increasing the performance and durability of the battery pack.

[0009] The cells inside the battery packs are surrounded by a thermally managed structure. This thermal management system is designed to prevent batteries from overheating. Overheating of batteries not only leads to poor performance, but also increases safety risks. Therefore, it is mandatory to use a cooling system in battery packs. The cooling system keeps the temperature of the battery cells at an optimum level, ensuring homogeneous temperature distribution within the pack and thus supporting the balanced operation of the cells.

[0010] To increase the safety of the battery packs, a battery management system (BMS) is also integrated that provides protection against overcharging, overdischarging and short circuits. This system ensures the balanced operation of the battery cells, extending the life of the battery pack and increasing its safety. In addition, the battery pack, which has a modular structure, can be adapted to different applications and combined in various configurations.

[0011] Lithium-ion batteries are one of the most widely used battery types today due to their high energy density and power. However, these batteries produce more heat compared to lower capacity batteries. Especially during discharge, the high heat generated by electrochemical reactions must be managed effectively. In order for the batteries to operate at optimum temperatures, the temperature distribution on their surfaces must be kept homogeneous and the temperature difference between the batteries must be a maximum of 3 degrees. This minimizes the capacity difference between batteries, ensures equal aging and extends battery life.

[0012] If the temperature in the batteries cannot be controlled, the cells cannot be cooled equally, which can lead to serious risks. These risks include problems such as thermal runaway, dendrite formation, increased internal resistance, gas formation and explosion. Thermal runaway triggers exothermic reactions that occur at high temperatures in batteries, which jeopardizes the safety of the battery pack. Increasing security risks of this type may require more complex and costly security measures. In addition, the shortening of the battery life and the need for early replacement increase the total cost of the system. Therefore, the design of a suitable and effective thermal management system is of great importance to keep the batteries at optimum temperature levels.

[0013] The most commonly used thermal management systems in the current art include air-cooled, liquid-cooled, and phase change material (PCM) cooling systems. Among these systems, liquid cooling stands out as the most effective method due to its high heat dissipation capacity. Liquid-cooled systems have also become more mature commercially and have a wider range of uses.

[0014] In liquid cooled battery packs, cooling plates are placed under or between the batteries. However, the cooling plates placed at the bottom effectively cool only the lower parts of the batteries and the cooling effect decreases in the upper parts. This causes an inhomogeneous temperature distribution on the battery surfaces and negatively affects the performance, efficiency and life of the batteries. Intermediate cooling plates are used to eliminate these problems. Intermediate cooling plates are placed between the batteries to provide a homogeneous temperature distribution and minimize temperature differences between batteries.

[0015] Today, in the current designs of intermediate cooling plates, performance cannot be increased to a sufficient level due to deficiencies in engineering calculations and geometric design errors. One of the most important factors affecting battery life is temperature, and effective cooling of batteries significantly extends the life of the cells. However, existing cooling plates cannot provide optimal homogeneous cooling due to their design.

[0016] The shortcomings and disadvantages of intermediate cooling plates in current applications can be listed as follows;

[0017] • Simple designs cannot provide adequate cooling performance.

[0018] • The inadequate geometric structure of the flow channels prevents the coolant from circulating homogeneously throughout the plate.

[0019] • Existing designs do not offer flexibility and convenience because they are not modular.

[0020] • Material and design do not adequately protect batteries from external factors.

[0021] • Since weight optimization is not performed, the rate of preference in energy storage systems is low. This increases the overall weight of the battery packs, reducing the energy density and portability of the system.

[0022] • Transporting the fluid in laminar regime at low flow rate causes inadequate heat transfer.

[0023] • The geometric structure of the flow channels causes the flow velocity to increase in some areas and this leads to irregularities in heat transfer.

[0024] Document number CN218448106 can be shown as an example of the state of the art in the research conducted in the literature. The document in question relates to the battery cell cooling device. In the said invention, a cooling device is disclosed which includes a box body and has a cooling unit in multiple layers for cooling multiple battery cells therein. In the cooling device, more than one battery cell is placed on the cooling plates, and the cooling of the battery cells is provided by the water passing through the channels communicating with the water inlet and water outlet arranged on the said cooling plates. However, in this application, since the cooling plates are placed under the batteries, only the lower parts of the batteries are effectively cooled and the cooling effect is reduced in the upper parts. This practice causes an inhomogeneous temperature distribution on the battery surfaces, which negatively affects the performance, efficiency and life of the batteries.

[0025] As a result, the above said drawbacks and the inadequacy of the prior art solutions about the subject have necessitated an improvement in the related technical field.

[0026] Purpose of the Invention

[0027] The present invention relates to a battery pack cooling system that eliminates the above-mentioned disadvantages and brings new advantages to the relevant technical field.

[0028] The main purpose of the invention is to present a cooling system that ensures homogeneous temperature distribution and minimum temperature difference in battery packs by means of intermediate cooling plates placed between battery cells.

[0029] The purpose of the invention is to provide a cooling system that maximizes the operating life and reliability of battery packs by increasing their performance and efficiency.

[0030] Another purpose of the invention is to present a cooling system that ensures effective distribution of the cooling liquid throughout the plate and equal heat absorption in each unit area, thanks to the inclined and curved structure of the cooling channels placed between the battery cells.

[0031] Another purpose of the invention is to present a cooling system that enables the heat to be transmitted quickly and effectively along the plate surface, thanks to the structure of the air channels in the cooling plates, thus providing efficient cooling by increasing heat transfer.

[0032] Another purpose of the invention is to present a cooling system that increases heat transfer by reducing pressure loss and reduces energy consumption and improves system efficiency, thanks to the fact that the air channels in the cooling plates are suitable for turbulent flow at low flow rates.

[0033] Another purpose of the invention is to present a cooling system that ensures that the cooling liquid is distributed homogeneously throughout the plate and the same temperature level is maintained at every point, thanks to the curved and inclined flow channels in the cooling plates, and that optimizes the performance of the batteries by maintaining their thermal balance with a uniform temperature distribution among the battery cells.

[0034] Another purpose of the invention is to present a cooling system that reduces weight thanks to thin-walled flow channels, increases structural integrity with its patterned structure, and protects batteries from possible hazards with cooling plates that prevent deformation.

[0035] Another purpose of the invention is to provide a cooling system that provides the same amount of energy storage capacity in the same dimensions by taking up less space thanks to the thin and compact structure of the cooling plates, and provides more efficient energy storage with both ease of transportation and installation and utilization of available space.

[0036] Another purpose of the invention is to provide a cooling system that provides ease of use by facilitating the manufacturing and assembly processes of the cooling plates thanks to the patterned structure of the flow channels in the cooling plates, thereby reducing labor costs in the commissioning function in battery packs of different configurations.

[0037] In order to fulfill all the above-mentioned objectives and those that may arise from the detailed description, the invention is a cooling system used in battery packs in the field of energy storage systems and comprising battery cells that are fixed to each other side by side in the battery pack and convert chemical energy into electrical energy, and it comprises: an intermediate cooling plate located between the battery cells and providing uniform heat transfer between the battery cells, a triangular shaped flow channel, arranged side by side in the intermediate cooling plate in opposite directions to each other and allowing the coolant passing through the intermediate cooling plate to be directed in a controlled manner within the intermediate cooling plate in order to provide heat transfer between the battery cells by absorbing the heat generated by the battery cells, a circular fluid inlet channel located on one edge of the intermediate cooling plate, allowing the coolant to enter the intermediate cooling plate at a certain speed and pressure, a circular fluid outlet channel located at the other edge of the intermediate cooling plate and allowing the coolant to exit the intermediate cooling plate at a certain speed and pressure, a flow passage opening located on the flow channels, allowing coolant to pass between the flow channels and allowing coolant to be evenly distributed on the intermediate cooling plate, a collector associated with a fluid inlet channel and a fluid outlet channel of the intermediate cooling plate, receiving coolant from a central cooling unit and transmitting the coolant to the intermediate cooling plates and sending the coolant leaving the intermediate cooling plates to the central cooling unit, and a sleeve for the connection between the intermediate cooling plates and the collectors.

[0038] The structural and characteristic features of the invention and all of its advantages shall be understood better with the figures and the detailed description given below in reference to the figures. Therefore, the assessment should be made by taking into account the said figures and detailed explanations.

[0039] Figures for Better Understanding of the Invention

[0040] Figure 1 : General view of the cooling system according to the invention.

[0041] Figure 2: A disassembled view of the cooling system according to the invention. Figure 3: A view of the assembled version of the cooling system according to the invention and the intermediate cooling plate detail.

[0042] Description of Part References

[0043] 10. Battery cell

[0044] 20. Intermediate cooling plate

[0045] 21 . Fluid inlet channel

[0046] 22. Flow channel

[0047] 23. Flow passage opening

[0048] 24. Fluid outlet channel

[0049] 30. Thermal pad

[0050] 40. Collector

[0051] 50. Sleeve

[0052] Detailed Description of the Invention

[0053] In this detailed description, the preferred alternatives of the cooling system which is the subject of the invention are explained only for the purpose of better understanding the subject and in a way that does not create any limiting effect.

[0054] Figures 1 a and 1 b show views of the cooling system according to the invention. Accordingly, the cooling system in its most basic form, comprises: battery cells (10) that are fixed to each other side by side in the battery pack and convert chemical energy into electrical energy, an intermediate cooling plate (20) located between the battery cells (10) and providing uniform heat transfer between the battery cells (10) by means of triangular flow channels (22) through which coolant flows, thermal pad (30) placed between the battery cells (10) and between the battery cell (10) and the heat sink plate (20), which improves heat transfer by filling the air gaps between the battery cells (10) and at the same time absorbs vibrations and mechanical shocks, a collector (40) associated with a fluid inlet channel (21 ) and a fluid outlet channel (24) of the intermediate cooling plate (20), receiving coolant from a central cooling unit and transmitting the coolant to the intermediate cooling plates (20) and sending the coolant leaving the intermediate cooling plates (20) to the central cooling unit, and a sleeve (50) for the connection between the intermediate cooling plates (20) and the collectors (40).

[0055] The battery cells (10) that make up the battery pack are the basic units that convert chemical energy into electrical energy. Battery cells (10) store electrical energy as chemical energy during charging and convert this energy back into electrical energy during discharge. The battery cells (10) contain positive and negative electrodes and an electrolyte that separates them.

[0056] While the battery pack is operating, each prismatic battery cell (10) generates heat during the charging and discharging processes. Managing this heat effectively is critical to maintaining the performance and life of the battery. In the cooling system which is the subject of the invention, an intermediate cooling plate (20) made of aluminum produced with the extrusion plate production technique is placed between both battery cells in order to balance the temperature of the cells. Said intermediate cooling plates (20) absorb the heat generated by the battery cells (10), minimizing the temperature difference between the battery cells (10) and increasing the overall efficiency of the battery pack. Accordingly, flow channels (22) are formed in the intermediate cooling plate (20) arranged side by side in opposite directions.

[0057] The flow channels (22) seen in Figure 3 are in the form of a triangle with curved upper and lower edges, and ensure that the cooling liquid is directed in a controlled manner within the intermediate cooling plate (20), thus ensuring optimal heat exchange between the cooling liquid and the battery cells (10). On the flow channels (22), there is a flow passage opening (23) in a square-shaped void structure. Said flow passage openings (23) ensure the passage of the cooling liquid between the flow channels (22) and maximize the cooling efficiency by ensuring that the cooling liquid is distributed evenly on the intermediate cooling plate (20).

[0058] The intermediate cooling plates (20) have a fluid inlet channel (21 ) on one side and a fluid outlet channel (4) on the other side. Said fluid inlet channel (21 ) has a circular profile structure and ensures that the cooling liquid enters the intermediate cooling plate (20) at a certain speed and pressure. Thanks to the circular profile structure of the fluid inlet channel (21 ), optimization of speed and pressure parameters has been achieved and efficient cooling has been achieved in the intermediate cooling plates (20). The fluid outlet channel (24) also has a circular profile structure and ensures that the cooling liquid exits the intermediate cooling plate (20) at a certain speed and pressure. Thanks to the circular profile structure of the fluid outlet channel (24), the coolant is effectively discharged from the intermediate cooling plates (20) after absorbing the heat from the battery cells (10).

[0059] Thermal pads (30) are placed between the battery cells (10) and between the battery cell and the cooling plate (20). Said thermal pads (30) are made of silicone-based material and contain filler materials that increase thermal conductivity. Thermal pads (30) improve heat transfer by filling the air gaps between the battery cells (10) when they are preferably bonded together. In addition, said thermal pads (30) have a flexible structure and absorb vibrations and mechanical shocks. This increases mechanical stability as well as thermal management.

[0060] The collectors (40) are connected to the fluid inlet channel (21 ) and fluid outlet channel (24) of the intermediate cooling plate (20) by means of sleeves (60). Said collectors (40) receive the cooling liquid from a central cooling unit and transmit it to the intermediate cooling plates (20) and send the cooling liquid coming out of the intermediate cooling plates (20) to the central cooling unit. In each intermediate cooling plate (20), the cooling liquid coming from the collector (40) enters the intermediate cooling plate (20) through the fluid inlet point (21 ) and travels through the intermediate cooling plate (20) along the inclined and curved flow channels (22). Thanks to the flow channels (22), the cooling liquid absorbs the same heat in each unit area and is distributed homogeneously along the intermediate cooling plate (20). This process creates an even temperature distribution between the battery cells (10) and prevents overheating.

[0061] Thanks to the fluid transition points (23), the cooling liquid is effectively circulated between the intermediate cooling plates (20) and the thermal balance of the entire battery pack is ensured. The cooling liquid entering the intermediate cooling plate (20) from the fluid inlet point (21 ) travels along the intermediate cooling plate (20) and collects the heat between all battery cells. The cooling liquid that collects the heat is carried out from the fluid outlet point (24) of the intermediate cooling plate (20) and collected in the collectors (40) and sent to the central cooling unit. This ensures that the battery cells (10) remain in ideal operating conditions, while the overall performance and reliability of the battery pack are increased and thermal balance is maintained. The sleeves (50) that provide the connection between the intermediate cooling plates (20) and the collectors (40) are made of elastomer material and have a flexible and durable structure. In this way, it ensures leak-proofness. Elastomer materials absorb vibrations and impacts because they have a low dynamic modulus. Elastomer materials also have a high coefficient of thermal expansion, allowing them to expand when exposed to heat and contract when cooled, thus adapting to thermal expansion.

Claims

1. CLAIMS1. A cooling system used in battery packs in the field of energy storage systems and comprising battery cells (10) that are fixed to each other side by side in the battery pack and convert chemical energy into electrical energy, characterized in that; it comprises: an intermediate cooling plate (20) located between the battery cells (10) and providing uniform heat transfer between the battery cells (10), a triangular shaped flow channel (22), arranged side by side in the intermediate cooling plate (20) in opposite directions to each other and allowing the coolant passing through the intermediate cooling plate (20) to be directed in a controlled manner within the intermediate cooling plate (20) in order to provide heat transfer between the battery cells (10) by absorbing the heat generated by the battery cells (10), a circular fluid inlet channel (21 ) located on one edge of the intermediate cooling plate (20), allowing the coolant to enter the intermediate cooling plate (20) at a certain speed and pressure, a circular fluid outlet channel (24) located at the other edge of the intermediate cooling plate (20) and allowing the coolant to exit the intermediate cooling plate (20) at a certain speed and pressure, a flow passage opening (23) located on the flow channels (22), allowing coolant to pass between the flow channels (22) and allowing coolant to be evenly distributed on the intermediate cooling plate (20), a collector (40) associated with a fluid inlet channel (21 ) and a fluid outlet channel (24) of the intermediate cooling plate (20), receiving coolant from a central cooling unit and transmitting the coolant to the intermediate cooling plates (20) and sending the coolant leaving the intermediate cooling plates (20) to the central cooling unit, and a sleeve (50) for the connection between the intermediate cooling plates (20) and the collectors (40).

2. A cooling system according to Claim 1 , characterized in that; said flow channels (22)are in the form of triangles with curved upper and lower edges.

3. A cooling system according to Claim 1 , characterized in that; said intermediate cooling plate (20) is made of aluminum.

4. A cooling system according to Claim 1 , characterized in that; said flow passage opening (23) has a square-shaped void structure.

5. A cooling system according to Claim 1 , characterized in that; it comprises a thermal pad (30) found between said battery cells (10) and between the battery cell (10) and the heat sink plate (20) and filling the air spaces left between the battery cells (10).

6. A cooling system according to Claim 5, characterized in that; said thermal pad (30) is made of a silicone-based material.

7. A cooling system according to Claim 5, characterized in that; said thermal pad (30) comprises a filler material that increases thermal conductivity.

8. A cooling system according to Claim 1 , characterized in that; said sleeve (50) is made of an elastomer material.

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