DESC:A SYSTEM FOR CELL LEVEL SHORT CIRCUIT PROTECTION IN A BATTERY PACK
This Application claims priority from a provisional patent application filed in India having Patent Application No. 201841034436, filed on December 12, 2018 and titled “A SYSTEM FOR CELL LEVEL SHORT CIRCUIT PROTECTION IN A BATTERY PACK”.
BACKGROUND
[0001] Embodiments of a present disclosure relate to a multi-cell battery pack and more particularly to a system for cell level short circuit protection in a battery pack.
[0002] A battery pack includes a set of a plurality of battery cells each with positive and negative terminals and a plurality of interconnects. Each of the battery cells convert chemical energy of substances stored in the battery cell into electrical energy. The plurality of interconnects provides electrical conductivity among the plurality of battery cells. The plurality of battery cells may be configured in a series, parallel or a combination of both arrangements to deliver a desired voltage, capacity, or power to an electrical device. In a multi cell lithium ion battery pack, when the positive and negative electrodes of the cells are short circuited inadvertently, it leads to thermal runaway condition resulting in fire or explosion. The short circuit between positive and negative electrodes of lithium ion cells may happen due to internal defects of the cell or when an external conductive part brings the positive and negative terminals of the cell in contact. In a multi-cell Lithium Ion battery pack, the cells are arranged in arrays of parallel and series combination. A parallel array of plurality of cells means all their positive terminals are connected together, and all their negative terminals are connected together. Cells are arranged in parallel array in order to obtain higher current output. A short circuit of any one cell in the parallel array either due to internal fault or an external fault will cause short circuit of all the remaining cells in the parallel array. Such condition is extremely dangerous and may lead to huge fire or explosion. In general, fuse protection is provided at battery pack level, but not at individual cell level. Such pack level fuses cannot protect cell level short circuit. Various approaches have been utilized to provide cell level fuses to overcome short circuit faults in lithium ion cells.
[0003] Specialty electronic components called as fuses are available in market which are widely used to protect electrical and electronic equipment during short circuit conditions. These fuses are inserted in line with the input/output terminals. The fuses are additional components which occupy space, add to complexity in assembly, and increase the overall cost of the battery pack.
[0004] In one implementation of a multi-cell battery pack, the cells are arranged in arrays of parallel and series combination. The cells are electrically connected in parallel with the help of metal plates. The metal plates are welded to the cells through different means such as resistance spot welding, laser welding, and ultrasonic welding. However, in order to introduce a fuse in-line with the metal interconnect plates of each cell, the metal plates have to be cut, and the fuse inserted between them either through soldering or mechanical bonding. The fuse will add to the overcall cost of the battery pack and the process involves complex steps and hence is expensive and time consuming.
[0005] In one another implementation of a multi-cell battery pack, the cells are arranged in arrays of parallel and series combination through metal plates and printed circuit boards. In order to introduce a fuse in-line with the battery call, the fuse is soldered onto the printed circuit board. The fuse and printed circuit board will add to the overcall cost of the battery pack and hence is expensive and time consuming.
[0006] Hence there is a need for an improved system for cell level short circuit protection in a lithium ion battery pack to address the aforementioned issue(s).
BRIEF DESCRIPTION
[0007] In accordance with an embodiment of the present disclosure, a system for cell level short circuit protection in a battery pack is provided. The system includes a metal plate placed inside the battery pack. The metal plate includes an electrical bridge metal structure. The electrical bridge structure includes a first side including a first set of weldable metal tab structures configured to couple a terminal of a corresponding plurality of cells of the battery pack. The first set of weldable metal tab structures comprise a neck down region configured to function as a fusible link and melt down in an event of short circuit of a cell from the plurality of cells. The electrical bridge structure also includes a second side comprising a second set of weldable metal tab structures configured to couple an opposite terminal of the corresponding plurality of cells of the battery pack. The electrical bridge structure is configured to couple the first side with the second side.
[0008] To further clarify the advantages and features of the present invention, a more particular description of the invention 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 invention and are therefore not to be considered limiting in scope. The invention will be described and explained with additional specificity and detail with the appended figures.
BRIEF DESCRIPTION OF DRAWINGS
The disclosure will be described and explained with additional specificity and detail with the accompanying figures in which:
[0009] FIG. 1 is a schematic representation of the battery pack with a system for cell level short circuit protection in accordance with an embodiment of the present disclosure;
[0010] FIG. 2 is schematic representation of system for cell level short circuit protection in the battery pack, depicting a metal plate in the battery pack of FIG. 1 in accordance with an embodiment of the present disclosure; and
[0011] FIG. 3 is a schematic representation of an embodiment of system of FIG. 1, depicting a portion of the metal plate of FIG. 2 in accordance with an embodiment of the present disclosure.
[0012] 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 invention 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 OF THE INVENTION
[0013] For the purpose of promoting an understanding of the principles of the invention, 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 invention is thereby intended. Such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as would normally occur to those skilled in the art are to be construed as being within the scope of the present invention. It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof.
[0014] 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 sub-systems or elements or structures or components preceded by "comprises... a" does not, without more constraints, preclude the existence of other devices, sub-systems, elements, structures, components, additional devices, additional sub-systems, 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.
[0015] 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 invention belongs. The system, methods, and examples provided herein are only illustrative and not intended to be limiting.
[0016] Embodiments of the present disclosure relate to a system for cell level short circuit protection in a battery pack. The system includes a metal plate placed inside the battery pack. The metal plate includes an electrical bridge metal structure. The electrical bridge structure includes a first side including a first set of weldable metal tab structures configured to couple a terminal of a corresponding plurality of cells of the battery pack. The first set of weldable metal tab structures comprise a neck down region configured to function as a fusible link and melt down in an event of short circuit of a cell from the plurality of cells. The electrical bridge structure also includes a second side comprising a second set of weldable metal tab structures configured to couple an opposite terminal of the corresponding plurality of cells of the battery pack. The electrical bridge structure is configured to couple the first side with the second side.
[0017] FIG. 1 is a block diagram representation of a system (10) in a battery pack (20) with protection circuits in accordance with an embodiment of the present disclosure. The system (10) includes a metal plate (30) placed inside the battery pack (20). In one embodiment, the metal plate (30) material may be one of Nickel, Copper, or a multi-layer composite of metallurgically bonded dissimilar metals such as nickel, copper, aluminium and stainless steel. As used herein the term "battery pack" refers to multiple individual battery cells contained within a single piece or multi-piece housing, wherein the individual battery cells are electrically interconnected to achieve the desired voltage and capacity for a particular application. In some embodiments, the battery pack (20) includes the plurality of cells (40). In such embodiment, each of the plurality of cells (40) are electrically coupled to corresponding side of the metal plate (30). In a series configuration, the plurality of battery cells (40) is connected in an alternate manner, such as the positive terminals of one of the plurality of battery cells (40) is connected to the negative terminals of the adjacent plurality of battery cells (40).
[0018] FIG. 2 is schematic representation of a system (10) for cell level short circuit protection in a battery pack (20), depicting a metal plate (30) of the battery pack (20) in accordance with an embodiment of the present disclosure. The metal plate (30) includes an electrical bridge metal structure (50). The electrical bridge metal structure (50) includes a first side (60), wherein the first side (60) includes a first set of weldable metal tab structures (70) which is configured to couple a terminal of the corresponding plurality of cells (40) of the battery pack (20). In one embodiment, the weldable metal tab structures (70) may be of leaf shape structure. The first set of weldable metal tab structures (70) comprise a neck down region (80) configured to function as a fusible link and melt down in an event of short circuit of a cell from the plurality of cells (40).
[0019] More clearly, each first weldable metal tab structure of the first set of weldable metal tab structures (70) includes the fusible link (100). The term “fusible link” as used herein refers to battery interconnect, typically a wire bond, that is designed to allow the expected current to pass without significant heating.
[0020] Moreover, the electrical bridge metal structure (50) also includes a second side (90) including a second set of weldable metal tab structures (100) which is configured to couple an opposite terminal of the corresponding plurality of cells (40) of the battery pack (20).
[0021] In addition, the electrical bridge metal structure (50) includes a plurality of holes (110) to receive a fixing means. In one embodiment, the fixing means may include screw-bolt or a rod. The plurality of holes (110) is configured to receive a rod to provide a structural support for the battery pack (20). In one embodiment, the plurality of holes (110) may be located at every pre-defined space on the metal plate (30).
[0022] FIG. 4 is a schematic representation of one embodiment of the present disclosure of FIG. 1, depicting a portion (120) of a metal plate (40) of FIG. 3 in accordance with another embodiment of the present disclosure. The portion (120) of the metal plate (30) includes the electrical bridge metal structure (130). The first side (140) of the electrical bridge metal structure (130) includes a first weldable metal tab structure (150) which is configured to couple a terminal of a first cell. The second side (160) of the electrical bridge metal structure (130) includes a second weldable metal tab structure (170) which is configured to couple an opposite terminal of a second cell. The first weldable metal tab structure (150) and the second weldable metal tab structure (170) are coupled in series with each other through the electrical bridge metal structure (130). The first weldable metal tab structure (150) includes a neck down region (180) which is configured to function as a fusible link and melt down in an event of short circuit of the corresponding cell and isolate it from the remaining plurality of cells (40).
[0023] The first weldable metal tab structure (150) of FIG. 3 is substantially similar to a first set of weldable metal tab structure (70) of FIG. 2. The second weldable metal tab structure (170) of FIG. 3 is substantially similar to a second set of weldable metal tab structures (100) of FIG. 3. Further, the electrical bridge metal structure (130) of FIG. 3 is substantially similar to electrical bridge metal structure (50) of FIG. 2. In addition, the neck down region (180) of FIG. 3 is substantially similar to neck down region (80) of FIG. 2.
[0024] Various embodiments of the system for cell level short circuit protection in a battery pack described above enables additional functionality of fusing open in the event of short circuit while efficiently providing electrical current conduction path for normal operational current.
[0025] As a result, improved battery pack performance, system reliability and system safety may be achieved while impacting only a small region of the nickel plate of the battery pack, and thus having only a minor impact on battery pack cost, complexity, weight and size. Further, the risk of damage and excessive heating is also minimized.
[0026] While specific language has been used to describe the invention, 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.
[0027] 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 dependent 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.
,CLAIMS:WE CLAIM:
1. A system (10) for cell level short circuit protection in a battery pack (20) comprising:
a metal plate (30) placed inside the battery pack (20), wherein the metal plate (30) comprises an electrical bridge metal structure (50), wherein the electrical bridge metal structure (50) comprises:
a first side (60) comprising a first set of weldable metal tab structures (70) configured to couple to a terminal of a corresponding plurality of cells (40) of the battery pack (20), wherein the first set of weldable metal tab structures (70) comprises a neck down region (80) configured to function as a fusible link and melt down in an event of short circuit of the corresponding cell and isolate the corresponding cell from the remaining plurality of cells (40); and
a second side (90) comprising a second set of weldable metal tab structures (100) configured to couple to opposite terminal of the corresponding plurality of cells (40) of the battery pack (20),
wherein the electrical bridge metal structure (50) is configured to couple the first side (60) and the second side (90) in series.
2. The system as claimed in claim 1, wherein the metal plate (30) is composed of at least one of Nickel, Copper, or a multi-layer composite of metallurgically bonded dissimilar metals comprising nickel, copper, aluminium and stainless steel.
3. The system (10) as claimed in claim 1, wherein each of the plurality of cells (40) of the battery pack (20) are electrically coupled to a corresponding side of the electrical bridge metal structure (50) in a series configuration, wherein the plurality of battery cells are connected in parallel with each other.
4. The system (10) as claimed in claim 1, wherein each of the neck down region (80) are introduced on the negative terminal or positive terminal of the corresponding plurality of cells (40).
5. The system (10) as claimed in claim 1, wherein the metal plate is partially covering the positive tab of the cells, wherein the metal plate comprises a plurality of vents for pressure release in the event of thermal runaway.
6. The system (10) as claimed in claim 1, wherein the plurality of cells (40) is connected in alternate manner comprising the positive terminals of one of the plurality of battery cells (40) is connected to the negative terminals of the adjacent plurality of battery cells.
7. The system (10) as claimed in claim 1, wherein the electrical bridge metal structure (50) comprises a plurality of holes (110) configured to receive a fixing means.

Dated this 12th day of December 2019

Signature

Vidya Bhaskar Singh Nandiyal
Patent Agent (IN/PA-2912)
Agent for the Applicant