Claims:WE CLAIM:
1. A thermal management system (10) for modular battery pack, comprising:
a heat sink (20) comprising of a set of four metal plates (40a, 40b, 40c and 40d) welded together at edges and provided with at least one of a plurality of fins (170), a plurality of dendrite structures (180) and a plurality of depressions (185) on outer side of the set of four metal plates (40a, 40b, 40c and 40d), wherein the heat sink (20) comprises:
at least one separator plate (50) configured to divide the heat sink (20) into at least two battery compartments;
at least one battery module (80a and 80b) configured to be housed in the each of the least two battery compartments, wherein each of the at least one battery modules (80a and 80b) comprises:
a set of thermal insulation plates (140) separating and insulating a plurality of cells (150);
a phase change material (160) surrounding the plurality of cells within confines of the set of thermal insulation plates (140) to absorb heat generated in radial direction;
a plurality of bus bars (90a and 90b) positioned in contact with the plurality of cells (150) forming continuity in electrical connections between the plurality of cells (150),
wherein the plurality of bus bars (90a and 90b) is configured to conduct heat generated in axial direction from the positive cell tabs and the negative cell tabs,
wherein the plurality of bus bars (90a and 90b) is fabricated with a plurality of leaf springs for enabling connection with each of the plurality of cells (150), and
wherein outer flat surface of the plurality of bus bars (90a and 90b) is adhesively coupled with a thermally conductive and electrically insulating substrate (110) to conduct heat from both of the plurality of bus bars (90a and 90b) to the surrounding heat sink (20).
2. The thermal management system (10) as claimed in claim 1, wherein the set of thermal insulation plates (140) configured to prevent thermal runaway in the plurality of cells (150).
3. The thermal management system (10) as claimed in claim 1, wherein the plurality of fins (170), the plurality of dendrite structures (180) and the plurality of depressions (185) are configured to generate air flow turbulence due to air passage thereby promoting the convection heat transfer.
4. The thermal management system (10) as claimed in claim 1, wherein the plurality of fins (170) is configured to be in at least one of horizontal orientation (170b), vertical orientation (170a) and any combination thereof forming a pattern of the plurality of fins (170).
5. The thermal management system (10) as claimed in claim 1, wherein the plurality of bus bars (90a and 90b) are configured to be connected, devoid of spot welding, with the plurality of cells via the plurality of leaf springs.
6. The thermal management system (10) as claimed in claim 1, wherein two or more battery modules (80a and 80b) are electrically coupled.
7. The thermal management system (10) as claimed in claim 1, further comprises a sealing means (60) for hermetically sealing a top lid (95) and a bottom lid (70) with the set of four metal plates (40a, 40b, 40c and 40d) to prevent ingression of at least one of dust, air and moisture.
8. The thermal management system (10) as claimed in claim 1, further comprises a set of two spacers (130) configured to position the positive cell tab and the negative cell tab of each of the plurality of cells (150) with respect to the leaf springs of the bus bar (90a and 90b).
9. The thermal management system (10) as claimed in claim 1, further comprises a set of bus bar frames (120) to position the plurality of bus bars (90a and 90b) with respect to the plurality of cells (150).
10. The thermal management system (10) as claimed in claim 1, wherein the plurality of bus bars (90a and 90b) comprises at least one of one or more single file bus bars (210), one or more double file bus bar (220) or any combination thereof.
11. The thermal management system (10) as claimed in claim 1, wherein the thermally conductive and electrically insulating substrate (110) comprises a thermal tape.
12. The thermal management system (10) as claimed in claim 1, wherein the plurality of bus bars (90) is electroplated with nickel to form a thin layer of nickel onto the plurality of bus bars (90) to prevent corrosion.

Dated this 14th day of October 2020

Signature

Vidya Bhaskar Singh Nandiyal
Patent Agent (IN/PA-2912)
Agent for the Applicant
, Description:FIELD OF INVENTION
[0001] Embodiments of a present disclosure relates to the field of managing performance of battery modules, and more particularly to a thermal management system for a modular battery pack.
BACKGROUND
[0002] Electric vehicles have developed into an important source of transportation due to the increasing concerns over fossil fuel depletion, environmental pollution, and ever escalating prices of crude oil. Electric vehicles include pure electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs).
[0003] For proper functioning of any electric vehicle, a major stress is given to the functioning of associated battery pack. When batteries are charging or discharging (powering of the motor) various complicated electrochemical reactions take place. Thermal behaviour of the batteries is coupled with such electrochemical reactions, i.e. the rate of reaction for these electrochemical reactions is directly proportional to the temperature of the cells. A higher reaction rate leads to higher heat generation.
[0004] Conventional electric vehicle battery packs often lack any thermal management system. Such battery packs normally have problems such as thermal runaway, over temperature, high temperature gradient, zero ingress protection and the like. Ingress protection includes protection from moisture and dust. In certain cases, hotspots are also created at centre of the battery stack, which leads to degradation of the cell’s performance and that of the battery pack as a whole.
[0005] There are certain known solutions for thermal management in battery packs. However, such known solutions are still marred with several performance and efficiency issues in terms of removing the heat generated in radial and axial directions in the cells. Furthermore, current designs of the battery pack lack proper balance of thermal management and structural integrity.
[0006] Hence, there is a need for an improved thermal management system for a battery pack and to therefore address the aforementioned issues.
BRIEF DESCRIPTION
[0007] In accordance with one embodiment of the disclosure, a thermal management system for modular battery pack is disclosed. The thermal management system includes a heat sink. The heat sink comprises of a set of four metal plates welded together at edges and further fabricated with at least one of a plurality of fins, a plurality of dendrite structures or a plurality of depressions on outer side of the set of four metal plates. The heat sink comprises of at least one separator plate.
[0008] The separator plate is configured to divide the heat sink into at least two battery compartments. The heat sink houses at least one battery module. At least one battery module is configured to be housed in the each of the least two battery compartments. At least one battery modules comprise a set of thermal insulation plates separating and insulating a plurality of cells, a phase change material surrounding the plurality of cells. The plurality of bus bars is positioned to provide the required series and parallel connections for the battery pack.
[0009] In another embodiment, the thermal management system further comprises of a sealing means for hermetically sealing a top lid and a bottom lid with the set of four metal plates to prevent ingression of at least one of dust, air or moisture and also egress of the phase change material from the thermal management system.
[0010] In yet another embodiment, the thermal management system further comprises of a set of two spacers configured to position the positive cell tab and the negative cell tab of each of the plurality of cells with respect to the leaf springs of the plurality of bus bars.
[0011] In an embodiment, the thermal management system further comprises of a set of bus bar frames to position the plurality of bus bars with respect to the plurality of cells.
[0012] To further clarify the advantages and features of the present disclosure, a more particular description of the disclosure will follow by reference to specific embodiments thereof, which are illustrated in the appended figures. It is to be appreciated that these figures depict only typical embodiments of the disclosure and are therefore not to be considered limiting in scope. The disclosure will be described and explained with additional specificity and detail with the appended figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The disclosure will be described and explained with additional specificity and detail with the accompanying figures in which:
[0014] FIG. 1 is a schematic representation of the thermal management system in accordance with an embodiment of the present disclosure;
[0015] FIG. 2 is an exploded view of the heat sink depicting connections of each parts in accordance with an embodiment of the present disclosure;
[0016] FIG. 3 is an exploded view illustrating housing of the battery module inside the heat sink in accordance with an embodiment of the present disclosure;
[0017] FIG. 4 is an exploded view of the thermal management system along with modular battery pack in accordance with an embodiment of the present disclosure;
[0018] FIG. 5 is an exploded representation of the modular battery pack and components in accordance with an embodiment of the present disclosure;
[0019] FIG. 6 is a schematic representation of the heat sink in accordance with an embodiment of the present disclosure;
[0020] FIG. 7 is a schematic representation of thermal insulation plates in accordance with an embodiment of the present disclosure;
[0021] FIG. 8 (a) is a schematic representation of a single file bus bar component corresponding to the plurality of bus bars fabricated with a plurality of leaf springs in accordance with an embodiment of the present disclosure; and
[0022] FIG. 8 (b) is a schematic representation of a double file bus bar component corresponding to the plurality of bus bars with a plurality of leaf springs in accordance with an embodiment of the present disclosure.
[0023] Further, those skilled in the art will appreciate that elements in the figures are illustrated for simplicity and may not have necessarily been drawn to scale. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the figures by conventional symbols, and the figures may show only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the figures with details that will be readily apparent to those skilled in the art having the benefit of the description herein.
DETAILED DESCRIPTION
[0024] For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Such alterations and further modifications in the illustrated online platform, and such further applications of the principles of the disclosure as would normally occur to those skilled in the art are to be construed as being within the scope of the present disclosure.
[0025] The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such a process or method. Similarly, one or more devices or subsystems or elements or structures or components preceded by "comprises... a" does not, without more constraints, preclude the existence of other devices, subsystems, elements, structures, components, additional devices, additional subsystems, additional elements, additional structures or additional components. Appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but not necessarily do, all refer to the same embodiment.
[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure belongs. The system, methods, and examples provided herein are only illustrative and not intended to be limiting.
[0027] In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings. The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.
[0028] Embodiments of the present disclosure relates to a thermal management system for a modular battery pack. The thermal management system enables efficient thermal management of heat generated in the battery, improves reliability, improves serviceability, improves recyclability, prevents premature failure, and prevents thermal runaway. Various heat controlling components are fabricated and implanted with the battery pack to achieve the aforementioned objectives. The present system maintains temperature of the battery module within the best suited range which thereby improves lifecycle and performance of the battery module.
[0029] FIG. 1 is a schematic representation of the thermal management system (10) in accordance with an embodiment of the present disclosure. The thermal management system (10) includes a heat sink (20) with a set of four metal plates, a top lid, and a bottom lid (not shown in FIG.1). The heat sink (20) also comprises of a plurality of fins positioned around outer surface of each wall of the set of four metal plates.
[0030] A separator plate (not shown in FIG.1) is positioned inside the heat sink (20) and configured to divide the heat sink (20) into at least two battery compartments. The separator plate is fabricated in pre-defined shape according to shape and size of the heat sink (20). Furthermore, the separator plate may be fabricated with suitable material such as metal, alloy, plastic, fibre etc. Furthermore, at least one battery modules comprise a plurality of cells separated and insulated by a set of thermal insulation plates (not shown in FIG.1). Battery modules is configured to be housed securely inside each of the battery compartments.
[0031] FIG. 2 is an exploded view of the heat sink (20) depicting connections of each part in accordance with an embodiment of the present disclosure. The heat sink (20) comprises of a set of four metal plates (40a, 40b, 40c and 40d) welded together lengthwise at edges. This approach is a departure from the existing way of fabrication of heat sink (20), where the entire heat sink (20) is extruded as a uni-body structure. Therefore, the present invention is able to bring down the fabrication cost of heat sink (20) while making the manufacturing process easier at low volumes. The set of four metal plates (40a, 40b, 40c and 40d) are fabricated with a plurality of fins (170) or a plurality of dendrite structures (180) or a plurality of depressions (185) or any combination thereof. The plurality of fins, the plurality of dendrite structures and the plurality of depressions are configured to generate air flow turbulence due to air passage thereby promoting the convectional heat transfer.
[0032] The plurality of fins (170) (as shown in FIG. 6) is configured to expel heat conducted by the heat sink (20) from a plurality of bus bars (not shown in FIG. 2) to the surrounding by convection heat transfer. In one specific embodiment, the plurality of fins (170) (as shown in FIG. 6) is distributed in an equi-spaced fashion. Alternatively, the plurality of fins (170) may also be variably spaced. In such embodiment, the plurality of fins (170) is further configured in a horizontal orientation (170b) or a vertical orientation (170a) or any combination thereof. Reiterating, that fins’ orientation (170a and 170b) is designed to improve the contact of air and improve the convection rate. In an embodiment, the plurality of fins (170) in horizontal orientation (170b) was able to bring more heat transfer area to come in contact with air flow which in turn gives better cooling.
[0033] Moreover, the components corresponding to the heat sink (20) such as the separator plate (50), the battery modules (80a and 80b) (not shown in FIG. 2) and surrounding set of four metal plates (40a, 40b, 40c and 40d), a top lid (95) and a bottom lid (70) are tightly sealed by sealing means (60). The sealing means (60) is affixed by screws (30) to the top lid (95) and the bottom lid (70). In an embodiment, the sealing means (60) includes, but not limited to, gaskets, linings, washers, industrial adhesives, rings and liners. The sealing means (60) enable hermetically sealing the top lid (95) (as shown in FIG. 3) and the bottom lid (70) with the set of four metal plates (40a, 40b, 40c and 40d) to prevent ingression of dust or air or moisture or any combination thereof. In an alternative embodiment, the bottom lid (70) is permanently coupled to bottom end of the heat sink (20) by welding, while the top lid (95) being affixed to top end of the heat sink (20) by using the sealing means (60) and the screws (30).
[0034] FIG. 3 is an exploded view illustrating housing of the battery modules (80a and 80b) inside the heat sink (20) in accordance with an exemplary embodiment of the present disclosure. The heat sink (20) is provided with one separator plate (50) which is configured to divide the heat sink (20) into two equal battery compartments. The battery module (80a) is housed in one battery compartment and the battery module (80b) housed in the other battery compartment. In an embodiment, the battery modules (80a and 80b) are housed such that they may be easily removed or swapped by opening the top lid (95).
[0035] FIG. 4 is an exploded view of the thermal management system (10) along with modular battery pack in accordance with an embodiment of the present disclosure. The thermal management system (10) is shown to have the set of four metal plates (40a, 40b, 40c and 40d) surrounding the two battery modules (80a and 80b), where the two battery modules (80a and 80b) are separated from each other by the separator plate (50) present in centre. Each of the battery modules (80a and 80b) are shown in exploded view to illustrate arrangement and connections of its parts. In such embodiment, each of the at least one battery modules (80a and 80b) comprises a plurality of bus bars (90a and 90b) connected to a plurality of cells (100) forming continuity in electrical connections between the plurality of cells (100) sandwiched in between them. In one embodiment, one or more plastic holders (210) may be used to structurally support the cells to form a stack of the plurality of cells
[0036] FIG. 5 is an exploded representation of the modular battery pack (80) and components in accordance with an embodiment of the present disclosure. Each of the at least one battery modules (80) comprise a plurality of cells (150), positioned in middle, separated and insulated by a set of thermal insulation plates (140). A phase change material (PCM) (160) is filled therein to surround each of the plurality of cells (150), whereby the phase change material (PCM) (160) is provided within confines of the set of thermal insulation plates (140) to absorb heat generated in radial direction. As used herein, the term “phase change material” is a substance which releases or absorbs sufficient energy at phase transition to provide useful heating or cooling. In one embodiment, the PCM comprises of material such as paraffin, salt hydrates and the like.
[0037] The PCM (160) absorbs majority of heat from each cell (150) surfaces by virtue of the material’s latent heat capacity. The PCM (160) provides uniformity in temperatures near and at the surface of the cells (150) as the same amount of PCM (160) is available for every cell. The PCM (160) helps to reduce the thermal gradient across the battery modules (80). In one specific embodiment, the sealing means (60) is used to prevent egress of the phase change material from the thermal management system.
[0038] In such embodiment, the set of thermal insulation plates (140) are configured to prevent thermal runaway within adjacent placed plurality of cells (150). The set of thermal insulation plates (140) provide thermal insulation between adjacent cells thereby preventing heat from being transferred from one cell to its neighbours.
[0039] Each of at least one battery modules (80a and 80b) also comprise of a plurality of bus bars (90a and 90b) positioned such that their leaf springs are in contact with the cell tabs. The plurality of bus bars (90a and 90b) provides electrical continuity between the plurality of cells (150) within the battery module. In such embodiment, the plurality of bus bars is manufactured from coupling of a single file bus bar and three double file bus bars (as shown in FIG. 9 (a) and FIG. 9 (b)).
[0040] Here, the plurality of bas bars (90a and 90b) is configured to conduct heat generated in axial direction from the positive cell tabs and the negative cell tabs. It is pertinent to note that wherein the plurality of bus bars (90a and 90b) is fabricated with a plurality of leaf springs for enabling connection with each of the plurality of cells (150). Further, outer flat surface of the plurality of bus bars (90a and 90b) is adhesively coupled with a thermally conductive and electrically insulating substrate (110) to conduct heat form the bus bars (90a and 90b) to the surrounding heat sink (20). In an embodiment, the thermally conductive and electrically insulating substrate is provided as one or more layers over the plurality of bus bars. In an exemplary embodiment, the thermally conductive and electrically insulating substrate (110) is in the form of a thermal tape.
[0041] Continuity in electrical connectivity between cells has been improved by metallic leaf spring design of the plurality of bus bars (90a and 90b) in vibration conditions. As this assembly does not require any spot welding as used regularly for battery connections, thereby reduces manufacturing time for battery packs. Therefore, the present invention saves time in assembly, reduces material cost for plurality bus bars, improves serviceability, reduce maintenance cost, improves recyclability of cells and helps in thermal management by conducting heat from the cell (150) tabs to the heat sink (20) with help of the thermally conductive and electrically insulating substrate (110) provided in-between them.
[0042] Moreover, each of at least one battery modules (80a and 80b) comprises a set of two spacers (130) configured to position the positive cell tab and the negative cell tab of each of the plurality of cells (150) with respect to the leaf springs of the bus bar (90a and 90b). The set of two spacers (130) is also configured to provide structural strength to the thermal management system. The spacers additionally provide structural strength to the cells. Additionally, each of the at least one battery modules also comprise a set of bus bar frames (140) to position the plurality of bus bars (90a and 90b) with respect to the plurality of cells (150). Whole bind structure is called as single battery module which may be inserted into the heat sink (20).
[0043] FIG. 6 is a schematic representation of the heat sink (20) in accordance with an exemplary embodiment of the present disclosure. The schematic representation clearly shows arrangement of the plurality of fins (170) over the heat sink (20). The plurality of fins are arranged in the horizontal orientation (170b) on the set of two metal plates (40b and 40c), and the plurality of fins (170) are arranged in the vertical orientation (170a) on the set of other two metal plates (40a and 40d). However, it is understood that the arrangement of the plurality of fins (170) over each of the set of four metal plates (40a, 40b, 40c and 40d) may vary as per the requirement.
[0044] FIG. 7 is a schematic representation of thermal insulation plates (140) in accordance with an embodiment of the present disclosure. The thermal insulation plates (140) comprise of two sets of plurality of plates arranged in criss-cross fashion and to form open boxes (190) to house individual cells, where first set of plurality of plates being perpendicular with respect to second set of plurality of plates. The thermal insulation plates (140) do not allow heat to flow through to other adjacent cells. Further, the PCM (160) is filled in the open boxes around the cells. In an exemplary embodiment, the open boxes (190) are in cuboidal construction for proper individual cell isolation.
[0045] In an exemplary embodiment, the plurality of bus bars (90) is fabricated with a plurality of leaf springs (200), whereby the leaf springs (200) are positioned with respect to position of the cell tabs. In such fabrication, the leaf springs (200) of the plurality of bus bars (90) are formed by upward cut out protrusions. The plurality of bus bars (90) also acts as a mediator and conducts heat from the cell tabs to the heat sink (20) via the thermally conductive and electrically insulating substrate (110).
[0046] FIG. 8 (a) is a schematic representation of a single file bus bar (210) component corresponding to the plurality of bus bars fabricated with a plurality of leaf springs in accordance with an embodiment of the present disclosure. The leaf springs (200) are positioned with respect to position of the cell tabs.
[0047] FIG. 8 (b) is a schematic representation of a double file bus bar (220) component corresponding to the plurality of bus bars with a plurality of leaf springs in accordance with an embodiment of the present disclosure. The leaf springs (200) are positioned with respect to position of the cell tabs. The single file bus bar (210) and a number of double file bus bar (220) are fused horizontally together to form the plurality of bus bars (90a & 90b) (as shown in FIG. 5).
[0048] In an exemplary embodiment, the plurality of bus bars (90) is fabricated with copper and electroplated with nickel to form a thin layer of nickel onto the plurality of bus bars (90) to prevent corrosion
[0049] The proposed invention maintains temperature of the battery pack within the best suitable range which thereby improves battery module’s lifecycle, performance, and safety. The heat conduction takes place in the direction from the cell tab to the bus bars to the heat sink to the fins and finally to atmospheric air. The heat generated by each of the plurality of cells is partially absorbed by phase change material (PCM) and remaining heat is carried out by conduction from each of the plurality of cells to surrounding environment by metallic bus bar.
[0050] It is pertinent to note that in the present invention if one cell goes into the thermal runaway condition, then other surrounding cells may not get impacted by the heat released from the damaged cell.
[0051] The present invention may also bring down the fabrication cost of heat sink (20) as well as the thermal management system (10). The present invention uses the heat sink which is fabricated by welding the set of four metal plates (40a, 40b, 40c and 40d) at edges. This is a simple solution for easy and cost-effective fabrication of heat sinks at low volumes.
[0052] The use of plurality of bus bars with leaf springs for battery connections does not require any spot welding. This reduces manufacturing time for battery packs, and improves the overall operations. Further, as there is no welding involved, the serviceability of the pack is improved. Additionally, at end of life, the cells can be recycled efficiently.
[0053] Furthermore, the present improved design of the battery pack also helps in creating modular batteries. Here, modularity is achieved without compromising the thermal management and structural integrity. Such improved design gives accessibility for battery swapping feature.
[0054] While specific language has been used to describe the disclosure, any limitations arising on account of the same are not intended. As would be apparent to a person skilled in the art, various working modifications may be made to the method in order to implement the inventive concept as taught herein.
[0055] The figures and the foregoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, order of processes described herein may be changed and are not limited to the manner described herein. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts need to be necessarily performed. Also, those acts that are not dependant on other acts may be performed in parallel with the other acts. The scope of embodiments is by no means limited by these specific examples.