Battery system, method for leak detection therein, and vehicle including the same

Abstract

The present invention relates to a battery system, a method for leak detection inside the battery system and a vehicle comprising the same, wherein the battery system comprises: a housing, comprising a housing frame and a base frame, wherein the housing frame and the base frame surround a housing space; at least one battery module, comprising a plurality of battery cells electrically connected to each other via a bus bar, wherein the battery module is arranged in the housing space; at least one tray, comprising a tray frame and a tray base; and a liquid detection system integrated with a battery management system, wherein the battery management system is suitable for detecting liquid inside the tray through the liquid detection system, wherein the liquid detection system comprises a high-voltage conductor, a first end of the high-voltage conductor is connected to the bus bar and a second end of the high-voltage conductor is arranged between the base frame and the tray base.

Description

Technical Field

[0001] The invention relates to a battery system, a method for leak detection within a battery system and a vehicle comprising at least one battery system. Background Art

[0002] In recent years, vehicles for the transportation of goods and people using electricity as a source of motion have been developed. Such electric vehicles are cars driven by motors using energy stored in rechargeable batteries. Electric vehicles can be powered only by batteries, or can be in the form of hybrid vehicles powered by, for example, fuel-based generators. In addition, the vehicle can include a combination of motors and conventional internal combustion engines. Typically, an electric vehicle battery (EVB) or traction battery is a battery used to power the propulsion of a battery electric vehicle (BEV). Electric vehicle batteries are different from starting batteries, lighting batteries, and ignition batteries because they are designed to provide power for a sustained period of time. Rechargeable batteries or secondary batteries differ from primary batteries in that they can be repeatedly charged and discharged, while primary batteries only provide irreversible conversion of chemical energy to electrical energy. Low-capacity rechargeable batteries are used as power sources for small electronic devices such as cellular phones, notebook computers, and portable cameras, while high-capacity rechargeable batteries are used as power sources for hybrid vehicles, etc.

[0003] Typically, a rechargeable battery includes: an electrode assembly including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode; a housing that receives the electrode assembly; and electrode terminals electrically connected to the electrode assembly. An electrolyte solution is injected into the housing to enable charging and discharging of the battery by electrochemical reactions of the positive electrode, the negative electrode, and the electrolyte solution. The shape of the housing (e.g., cylindrical or rectangular) depends on the intended use of the battery. Lithium-ion (and similar lithium polymer) batteries, widely known through their use in laptop computers and consumer electronics, dominate the latest group of electric vehicles under development.

[0004] A rechargeable battery can be used as a battery module formed by a plurality of unit battery cells connected in series and / or in parallel to provide high energy density, particularly for motor driving of hybrid vehicles. That is, a battery module is formed by interconnecting electrode terminals of the plurality of unit battery cells depending on the required amount of electricity to realize a high-power rechargeable battery.

[0005] A battery pack is a group of any number of (preferably identical) battery modules. They can be configured in series, parallel, or a mixture of both to provide the required voltage, capacity, or power density. The components of a battery pack include the individual battery modules and the interconnectors that provide conductivity between them.

[0006] The mechanical integration of such a battery pack requires appropriate mechanical connections between the individual components (e.g. of the battery modules) and between them and the supporting structure of the vehicle. These connections must remain functional and safe during the average service life of the battery system. In addition, installation space and interchangeability requirements must be met, especially in mobile applications.

[0007] Mechanical integration of the battery module can be achieved by providing a carrier frame and by placing the battery module thereon. Fixing the battery cells or battery modules can be achieved by suitable recesses in the frame or by mechanical interconnectors such as bolts or screws. Optionally, the battery module is restrained by fastening side plates to the sides of the carrier frame. In addition, cover plates can be fixed above and below the battery module.

[0008] The carrier frame of the battery pack is mounted to the load-bearing structure of the vehicle. In case the battery pack should be fixed to the bottom of the vehicle, the mechanical connection can be established from the bottom side, for example by bolts passing through the carrier frame of the battery pack. The carrier frame is usually made of aluminum or an aluminum alloy to reduce the overall weight of the construction.

[0009] Despite any modular structure, a battery system according to the prior art typically includes a battery housing that serves as a housing to seal the battery system from environmental influences and provide structural protection for the components of the battery system. The battery system with the housing is typically installed entirely in its application environment (e.g., an electric vehicle). Therefore, replacement of a defective system part (e.g., a defective battery submodule) requires first disassembling the entire battery system and removing its housing. Even defects in small and / or inexpensive system parts may result in disassembly and replacement of the entire battery system and its separate repair. Since high-capacity battery systems are expensive, large and heavy, the process proves to be cumbersome and storage of bulky battery systems (e.g., in a mechanic's workshop) becomes difficult.

[0010] In order to provide thermal control of the battery pack, a thermal management system is required to safely use at least one battery module by effectively dissipating, releasing and / or dissipating the heat generated from its rechargeable battery. If the dissipation / release / dissipation is not adequately performed, temperature deviation occurs between the individual battery cells, so that at least one battery module cannot generate the desired amount of electricity. In addition, an increase in the internal temperature may cause an abnormal reaction to occur therein, so that the charging and discharging performance of the rechargeable battery deteriorates and the life of the rechargeable battery is shortened. Therefore, cell cooling for effectively dissipating / releasing / dissipating the heat from the cell is required.

[0011] Therefore, the battery system may include a cooling system for cooling the battery. Liquid cooling systems are usually used instead of air cooling systems because the latter have lower performance compared to liquid cooling systems. However, there may always be a risk of leakage problems with liquid cooling systems, especially when the battery system is not sealed. The cooling liquid from the battery module may leak in the battery housing. Therefore, the battery housing will be filled with a liquid, which is the cooling liquid leaked from the battery module. In addition, the cooling liquid is conductive. Therefore, when the liquid inside the battery housing reaches a certain level so that the liquid contacts the battery module, safety-related problems such as insulation failure, electrolysis, and the release of explosive gases may occur.

[0012] EP2506360A1 discloses a battery pack having a housing including batteries and a liquid leakage detection system including conductive wire grids and an open cell foam layer arranged between the conductive wire grids, and DE10 2013201411A1 discloses a housing including a sensor designed to detect leaked liquid in the housing.

[0013] It is therefore an object of the present invention to overcome or reduce at least some of the disadvantages of the prior art and to provide a battery system capable of detecting the presence of liquid within the housing of the battery system. Summary of the invention

[0014] Embodiments of the present disclosure attempt to solve at least one of the problems existing in the prior art to some extent. Specifically, a battery system for a vehicle is provided. The battery system includes: a housing, including a housing frame and a base frame, wherein the housing frame and the base frame surround a housing space; at least one battery module, including a plurality of battery cells electrically connected to each other by a bus bar, wherein the battery module is arranged in the housing space; at least one tray, including a tray frame and a tray base; and a liquid detection system integrated with a battery management system, wherein the battery management system is suitable for detecting liquid inside the tray through the liquid detection system, wherein the liquid detection system includes a high voltage conductor, the first end of the high voltage conductor is connected to the bus bar and the second end thereof is arranged between the base frame and the tray base. The battery system may also include a cooling system with a cooling liquid, wherein the battery module is suitable for receiving the cooling liquid for cooling. The tray frame may be connected to the base frame, and the tray frame and the tray base may be electrically insulated; the tray base may be located at a predetermined distance from the base frame.

[0015] According to another aspect of the present invention, a method for leak detection inside a battery system is provided. The method comprises the following steps:

[0016] I. Provide a battery system, the battery system comprising:

[0017] (i) a housing, comprising a housing frame and a base frame, wherein the housing frame and the base frame surround a housing space;

[0018] (ii) a cooling system having a cooling liquid;

[0019] (iii) at least one battery module comprising a plurality of battery cells electrically connected to each other, wherein the battery module is disposed in the housing space, wherein the battery module is adapted to receive a cooling liquid for cooling;

[0020] (iv) at least one pallet comprising a pallet frame and a pallet base; and

[0021] (v) a liquid detection system integrated with the battery management system, wherein the battery management system is adapted to detect liquid inside the tray via the liquid detection system, wherein the liquid detection system comprises a high voltage conductor having a first end connected to the bus bar and a second end disposed between the base frame and the tray base;

[0022] II. Monitoring the reduction of cooling liquid inside the cooling system through the battery management system;

[0023] III. Monitoring the increase of liquid inside the tray through the battery management system;

[0024] IV. comparing, by the battery management system, a decrease in cooling liquid within the cooling system and an increase in liquid within the tray; and

[0025] V. Verify through the battery management system that if a decrease in cooling liquid inside the cooling system corresponds to an increase in liquid inside the tray, then the liquid inside the tray is cooling liquid.

[0026] According to another aspect of the present invention, a vehicle is provided, the vehicle comprising at least one battery system as described above.

[0027] Further aspects of the invention can be learned from the dependent claims or the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Features will become apparent to those skilled in the art by describing in detail exemplary embodiments with reference to the accompanying drawings, in which:

[0029] Figure 1 A schematic perspective view showing a battery system with a high voltage conductor according to an embodiment;

[0030] Figure 2 A schematic perspective view showing a battery system having a high voltage conductor and a low voltage conductor according to an embodiment;

[0031] Figure 3A schematic perspective view showing a battery system having a liquid reservoir according to an embodiment;

[0032] Figure 4 A schematic diagram showing a high voltage conductor that is part of a bus bar according to an embodiment;

[0033] Figure 5 A schematic diagram showing a high voltage conductor connected to a bus bar according to an embodiment;

[0034] Figure 6 A flow chart showing a method for leak detection inside a battery system according to an embodiment;

[0035] Figure 7 A flow chart showing a step of a method for leak detection inside a battery system according to an embodiment;

[0036] Figure 8 A schematic perspective view showing a battery system having a liquid reservoir according to an embodiment;

[0037] Fig. 9 A schematic perspective view showing a battery system having a liquid reservoir according to an embodiment; and

[0038] Fig.10 A schematic perspective view of a battery system having a liquid reservoir according to an embodiment is shown. DETAILED DESCRIPTION

[0039] By referring to the following detailed description of the embodiments and the accompanying drawings, the features of the inventive concept and its implementation method can be more easily understood. Hereinafter, the example embodiments will be described in more detail with reference to the accompanying drawings, in which the same reference numerals always represent the same elements. However, the present invention can be implemented in various different forms and should not be interpreted as being limited to the embodiments shown here. On the contrary, these embodiments are provided as examples so that the present disclosure will be thorough and complete, and the aspects and features of the present invention will be fully conveyed to those skilled in the art. Therefore, it is not necessary to describe processes, elements and techniques for a person of ordinary skill in the art to fully understand the aspects and features of the present invention. Unless otherwise specified, the same reference numerals represent the same elements throughout the drawings and text descriptions, and therefore, their descriptions will not be repeated. In the drawings, for clarity, the relative sizes of elements, layers and regions may be exaggerated.

[0040] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. In addition, the use of "may" when describing embodiments of the present invention refers to "one or more embodiments of the present invention."

[0041] It will be understood that although the terms "first" and "second" are used to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. For example, without departing from the scope of the present invention, a first element can be named as a second element, and similarly, a second element can be named as a first element.

[0042] In the following description of the embodiments of the present invention, terms in the singular form may include plural forms unless the context clearly indicates otherwise.

[0043] It will also be understood that the terms “comprise” or “include” specify properties, regions, fixed numbers, steps, processes, elements, components and combinations thereof, but do not exclude other properties, regions, fixed numbers, steps, processes, elements, components and combinations thereof.

[0044] For ease of explanation, spatial relational terms such as "below", "below", "below", "below", "above", "on", etc. may be used here to describe the relationship of one element or feature to another (some) element or feature as shown in the drawings. It will be understood that, in addition to the orientations drawn in the drawings, the spatial relational terms are intended to cover different orientations of the device in use or operation. For example, if the device in the drawings is turned over, the elements described as being "below" or "below" or "below" other elements or features will be oriented as being "above" other elements or features. Therefore, the example terms "below" and "below" can cover both above and below orientations. The device can be oriented otherwise (for example, rotated 90 degrees or in other orientations), and the spatial relational descriptors used here should be interpreted accordingly. It will also be understood that when a part or element is referred to as being "above" or "on" another part or element, it can be directly on the other part or element, or there can also be intervening parts or elements.

[0045] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and / or this specification, and should not be interpreted as an idealized or overly formal meaning, unless explicitly defined as such herein.

[0046] Figure 11 is a perspective view showing a battery system 10 according to an exemplary embodiment. The battery system 10 includes a housing 11, and the housing 11 includes a housing frame 12a and a substrate frame 12b (shown by a dotted line). The substrate frame 12b has a rectangular shape and may be composed of a conductive material such as copper. The housing frame 12a and the substrate frame 12b surround a housing space 13. The battery system 10 includes three battery modules M1, M2, and M3, namely a first battery module M1, a second battery module M2, and a third battery module M3, wherein the battery modules M1, M2, and M3 are arranged in the housing space 13. Each of the battery modules M1, M2, and M3 includes a module housing 24 and a module substrate 25, respectively, wherein each of the module housing 24 and the module substrate 25 surrounds a corresponding module space 26. The module substrate 25 of each of the battery modules M1, M2, and M3 is supported by the substrate frame 12b. In other words, the battery modules M1, M2, and M3 are placed on the substrate frame 12b. The module base 25 of each of the battery modules M1, M2, and M3 is coupled to the base frame 12b by mechanical means known to those skilled in the art. It is also contemplated that the dimensions of the battery modules M1, M2, and M3 can be adapted so that the battery modules M1, M2, and M3 are suitably disposed in the housing space 13 and supported by the housing frame 12a and the base frame 12b of the battery system 10.

[0047] The first battery module M1 includes a plurality of battery cells 14, the second battery module M2 includes a plurality of battery cells 15, and the third battery module M3 includes a plurality of battery cells 16. In other words, the plurality of battery cells 14, 15, and 16 are disposed in the corresponding module space 26 of each corresponding battery module M1, M2, and M3. Each of the plurality of battery cells 14, 15, and 16 of the respective battery modules M1, M2, and M3 is electrically connected to each other through a bus bar. According to an exemplary embodiment, the plurality of battery cells 14 of the first battery module M1 are connected through a bus bar 18, and the plurality of battery cells 16 of the third battery module M3 are connected through a bus bar 19. The plurality of battery cells 14 of the first battery module M1 are electrically connected to the plurality of battery cells 15 of the second battery module M2 through a bus bar 20. The plurality of battery cells 15 of the second battery module M2 are electrically connected to the plurality of battery cells 16 of the third battery module M3 through a bus bar 21. In an exemplary embodiment, the bus bars 18, 19, 20, and 21 are made of aluminum. Of course, in alternative embodiments, busbars 18, 19, 20 and 21 may be made of other metals or metal alloys or conductive materials known to those skilled in the art. In addition, each of busbars 18, 19, 20 and 21 may be made of different materials independent of each other.

[0048] The battery cells 14, 15 and 16 according to an embodiment may include an electrode assembly (not shown in the drawings) and a housing 17 for accommodating the electrode assembly, the housing 17 accommodating an electrolyte. The electrode assembly may be formed into a jelly roll type electrode assembly by spirally winding a positive electrode and a negative electrode with a separator (not shown in the drawings) therebetween. The electrolyte may be made of a lithium salt (such as LiPF6 or LiBF4) and an organic solvent (such as EC, PC, DEC, EMC or EMC). The electrolyte solution may be in a liquid, solid or gel state.

[0049] The battery cells 14, 15, and 16 may further include a cap assembly 22 for sealing the opening of the housing 17. The battery cells 14, 15, and 16 are described as non-limiting examples of lithium-ion secondary batteries configured to have a prismatic (or rectangular) shape. The housing 17 may be configured to have a substantially rectangular parallelepiped shape, and an opening may be formed on one side thereof. The housing 17 may be formed of a metal such as aluminum.

[0050] The housing 17 may further include a substrate 27, so that the substrate 27 and the side surfaces of the battery cells 14, 15 and 16 form a space for accommodating an electrode assembly and an electrolyte. In addition, the housing 17 is hermetically sealed by the cap assembly 22, wherein the substrate 27 and the cap assembly 22 are parallel to each other. The cap assembly 22 is provided with a positive electrode terminal 23 and a negative electrode terminal 23' having different polarities and a vent (not shown in the drawings). The vent is a safety mechanism of the battery cells 14, 15 and 16, which serves as a channel through which the gas generated in the battery cells 14, 15 and 16 is discharged to the outside of the battery cells 14, 15 and 16.

[0051] The battery system 10 includes a cooling system 28 having a cooling liquid 29, wherein the cooling system 28 is configured to provide the cooling liquid 29 to each of the battery modules M1, M2, and M3 along respective paths 30, 31, and 32 for cooling the respective battery modules M1, M2, and M3. The battery modules M1, M2, and M3 are adapted to receive the cooling liquid 29 for cooling, so that the cooling liquid 29 can absorb heat energy that can be released by the battery cells 14, 15, and 16 during operation of the battery system 10.

[0052] The battery system 10 includes a tray 33. The tray 33 includes a tray frame 34 and a tray base 35. The tray frame 34 is coupled to the tray base 35 by welding or mechanical means known to those skilled in the art. The tray frame 34 and the tray base 35 are electrically insulated. The tray base 35 is located at a predetermined distance from the base frame 12b so that the tray frame 34 and the tray base 35 surround a tray space 36. The tray space 36 is configured to receive a liquid 37, which may be a part of the cooling liquid 29 that may leak from at least one of the battery modules M1, M2, and M3 and be collected in the tray space 36. The base frame 12b may be in the form of a frame skeleton structure (not shown in the drawings) so that the base frame 12b includes an outer periphery of the module base 25 for supporting the corresponding battery modules M1, M2, and M3 and a hollow space therebetween, so as to be able to reduce the weight of the battery system 10 and enable the liquid 37 to pass therethrough, wherein the liquid 37 may leak from the battery modules M1, M2, and M3 into the tray space 36. In addition, the base frame 12b may be in the form of a grid configured to support the battery modules M1, M2, and M3 placed thereon and also to allow the liquid 37 to pass therethrough, wherein the liquid 37 may leak from the battery modules M1, M2, and M3 into the tray space 36. The tray frame 34 may be coupled to the base frame 12b by mechanical couplings such as bolts and rivets, or may be welded or coupled to the base frame 12b by mechanical means known to those skilled in the art. The tray frame 34 and the base frame 12b may be coupled so that they can be separated when necessary.

[0053] The battery system 10 can be integrated in a vehicle that can be driven electrically (not shown in the drawings), wherein the tray base 35 can be coupled to the chassis of the vehicle. In another embodiment (not shown in the drawings), the base frame 12b can be coupled to the chassis of the vehicle on one side of the chassis so that the housing 11 of the battery system 10 is disposed on the chassis. The tray base 35 can be coupled to the other side of the chassis so that liquid 37 that may leak from at least one of the battery modules M1, M2, and M3 is collected in the tray space 36. In addition, the battery system 10 may include more than one tray 33 that is coupled to the housing 11. This is advantageous because it can allow the predetermined distance between the tray base 35 and the base frame 12b to be reduced to receive the same amount of leaked liquid 37 compared to a single tray 33.

[0054] The battery system 10 includes a battery management system 38, which includes a microprocessor 39 and is configured to manage the charge / discharge of the battery system 10. In addition, the battery system 10 includes a liquid detection system 40 integrated with the battery management system 38. The liquid detection system 40 can be integrated in the battery management system 38 so that the liquid detection system is partially or completely a part of the battery management system 38. The battery management system 38 is adapted to detect the liquid 37 inside the tray 33 through the liquid detection system 40. In other words, when there is a leak from one of the battery modules M1, M2, and M3 so that the cooling liquid 29 therein leaks out as liquid 37 into the tray 33, the liquid detection system 40 is adapted to detect a change in a characteristic (e.g., resistance) in the battery system 10 and send a signal to the battery management system 38. Upon receiving the signal from the liquid detection system 40, the battery management system 38 is able to detect the liquid 37 inside the tray 33.

[0055] As shown in the drawings, the liquid detection system 40 is integrated with the battery management system 38. The liquid detection system 40 includes a high voltage conductor 41 located outside the battery management system 38. A first end 41a of the high voltage conductor 41 is connected to the bus bar 18, and a second end 41b of the high voltage conductor 41 is disposed between the base frame 12b and the tray base 35. In other words, the high voltage conductor 41 is electrically connected to an electrode of one of the battery cells 14, 15, and 16 at the first end 41a, and is at least partially disposed under the module base 25 of the battery modules M1, M2, and M3 at the second end 41b.

[0056] The liquid detection system 40 includes a resistance monitoring system 42 configured to monitor the resistance between the high voltage conductor 41 and the tray base 35. Figures 1 to 3 and Figures 8 to 10As shown, the resistance monitoring system 42 of the liquid detection system 40 is part of the battery management system 38. The resistance monitoring system 42 is electrically coupled to the high voltage conductor 41 through an electrical conductor 43. The resistance monitoring system 42 is electrically coupled to the tray base 35 through an electrical conductor 44. The resistance monitoring system 42 is configured to output a resistance signal indicating the resistance level between the high voltage conductor 41 and the tray base 35. In the absence of a leak (i.e., liquid 37), the resistance level between the high voltage conductor 41 and the tray base 35 may be a value corresponding to the value of the isolation resistance. In the event that the cooling liquid 29 leaks from at least one of the battery modules M1, M2, and M3, the liquid 37 collected inside the tray 33 may reach a level corresponding to the distance of the position of the second end 41b of the high voltage conductor 41 from the tray base 35. In this case, the liquid 37 forms a conductive path, due to which the resistance level between the high voltage conductor 41 and the tray base 35 is reduced. Depending on the position of the second end 41b of the high voltage conductor 41, the threshold resistance value is experimentally or empirically determined. When the resistance monitoring system 42 outputs a resistance signal at a certain moment, at this moment, the microprocessor 39 determines whether the resistance level based on the output resistance signal is less than or equal to the threshold resistance value. In the case where the level of the collected liquid 37 has not yet reached a level corresponding to the distance of the position of the second end 41b of the high-voltage conductor 41 from the tray base 35 (i.e., the liquid 37 has not yet contacted the second end 41b), the resistance level determined by the microprocessor 39 is greater than the threshold resistance value. Therefore, the presence of the liquid 37 inside the tray 33 is not detected. However, at a later moment, when a predetermined amount of cooling liquid 29 leaks from at least one of the battery modules M1, M2, and M3, the resistance level determined by the microprocessor 39 from the resistance signal output by the resistance monitoring system 42 at this moment is less than or equal to the threshold resistance value. Therefore, the liquid 37 inside the tray 33 can be detected.

[0057] However, other types of methods for detecting the liquid 37 inside the tray 33 by detecting a characteristic change based on the battery system 10 that may be known to those of ordinary skill in the art may be employed. For example, the high voltage conductor 41 is connected to the bus bars 18, 19, 20, and 21 and has a voltage potential corresponding to the voltage potential of the bus bars 18, 19, 20, and 21, while the tray base 35 has the same ground potential as the battery management system 38. This enables a predetermined voltage potential difference to be formed between the high voltage conductor 41 and the tray base 35. When there is no liquid 37 between the high voltage conductor 41 and the tray base 35, there may be no electrical connection between the high voltage conductor 41 and the tray base 35. Therefore, a signal based on a predetermined resistance value may be sent to the battery management system 38, and the predetermined resistance value may be set to correspond to the absence of an electrical connection between the high voltage conductor 41 and the tray base 35. Similarly, a signal based on a threshold current value may be sent by the liquid detection system 40 to the battery management system 38, and the threshold current value is caused by the absence of an electrical connection between the high voltage conductor 41 and the tray base 35. Based on this, the battery management system 38 may determine that no liquid 37 is present in the tray 33 .

[0058] When the liquid 37 inside the tray 33 rises to a level such that it contacts at least the second end 41b of the high voltage conductor 41, an electrical connection is established between the high voltage conductor 41 and the tray base 35. Therefore, a signal based on a change in resistance value can be sent to the battery management system 38, and the change in resistance value can be set to correspond to the electrical connection established between the high voltage conductor 41 and the tray base 35 due to the liquid 37. Similarly, a signal based on a change in current value caused by the electrical connection established between the high voltage conductor 41 and the tray base 35 due to the liquid 37 can be sent to the battery management system 38 by the liquid detection system 40. Based on this, the battery management system 38 can detect the liquid 37 inside the tray 33.

[0059] In order to be able to detect the presence of the liquid 37 inside the tray 33 at an earlier stage (i.e., at a level lower than the position of the second end 41b), the liquid detection system 40 further includes a low-voltage conductor 45, the first end 45a of which is connected to the battery management system 38 and the second end 45b of which is disposed between the second end 41b of the high-voltage conductor 41 and the tray base 35. In other words, the presence of the liquid 37 leaking from at least one of the battery modules M1, M2, and M3 can be detected earlier (i.e., when the level of the liquid 37 collected in the tray 33 is lower than the position of the second end 41b). Therefore, the presence of the liquid 37 at a level farther from the module base 25 of the battery modules M1, M2, and M3 is detected by the battery management system 38 with the aid of the low-voltage conductor 45 of the liquid detection system 40. Therefore, with the aid of such a redundant sensor (i.e., the additional low-voltage conductor 45 together with the high-voltage conductor 41), a higher reliability for detecting the liquid 37 inside the tray 33 can be achieved.

[0060] In addition, the resistance monitoring system 42 is configured to monitor the resistance between the low voltage conductor 45 and the tray base 35. Since the first end 45a is connected to the battery management system 38, the resistance monitoring system 42 integrated with the battery management system 38 is electrically connected to the low voltage conductor 45. The resistance monitoring system 42 is electrically connected to the tray base 35 through the electrical conductor 44. The resistance monitoring system 42 is configured to output a resistance signal indicating the resistance level between the low voltage conductor 45 and the tray base 35. In the absence of leakage (i.e., liquid 37), the resistance level between the low voltage conductor 45 and the tray base 35 may be a value corresponding to a predetermined set value. In the event that the cooling liquid 29 leaks from at least one of the battery modules M1, M2, and M3, the liquid 37 collected inside the tray 33 may reach a level corresponding to the distance of the position of the second end 45b of the low voltage conductor 45 from the tray base 35. In this case, the liquid 37 forms a conductive path, due to which the resistance level between the low voltage conductor 45 and the tray base 35 is reduced. When the resistance monitoring system 42 outputs a resistance signal at a certain moment, then at this moment, the microprocessor 39 determines whether the resistance level based on the output resistance signal is less than or equal to a predetermined set value. In the case where the level of the collected liquid 37 has not yet reached a level corresponding to the distance of the position of the second end 45b of the low-voltage conductor 45 from the tray base 35 (i.e., the liquid 37 does not contact the second end 45b), the resistance level determined by the microprocessor 39 is greater than the predetermined set value. Therefore, the presence of the liquid 37 in the tray 33 is not detected. However, at a subsequent moment, when a predetermined amount of cooling liquid 29 leaks from at least one of the battery modules M1, M2, and M3, then at this moment, the resistance level determined by the microprocessor 39 from the resistance signal output by the resistance monitoring system 42 is less than or equal to the threshold resistance value. Therefore, the liquid 37 inside the tray 33 can be detected. However, other types of methods known to those of ordinary skill in the art for detecting the liquid 37 inside the tray 33 by detection based on characteristic changes in the battery system 10 may be used.

[0061] In one embodiment, the battery management system 38 and the tray 33 may be connected to the same ground potential, wherein the battery management system 38 is adapted to detect liquid 37 between the low voltage conductor 45 and the tray base 35. Furthermore, the low voltage conductor 45 may include a resistor.

[0062] like Figure 3As shown, according to one embodiment, the tray base 35 comprises an inclined surface 46. The tray base 35 having the inclined surface 46 comprises at least one reservoir 47, for example one reservoir 47. The reservoir 47 is located at the lowest point on the slope of the inclined surface 46, so that in the event of a leakage of the cooling liquid 29, the liquid 37 first flows directly into the reservoir 47 due to gravity and is collected inside the reservoir 47. The reservoir 47 is in the form of a cylindrical volume, which comprises a reservoir base 48 and a reservoir wall 49. The reservoir base 48 and the reservoir wall 49 are such that they surround a reservoir space 50, in which the leaked liquid 37 is first collected after the leakage. The reservoir 47 comprises an open end at the top, through which the leaked liquid 37 enters the reservoir space 50. In other words, the tray base 35 includes the inclined surface 46 (rather than a flat surface) and the liquid reservoir 47 so that the liquid 37 can be detected for very little leakage of the liquid 37 from at least one of the battery modules M1 , M2 , and M3 .

[0063] The second end 41b of the high voltage conductor 41 and the second end 45b of the low voltage conductor 45 are arranged in the reservoir space 50, wherein the second end 45b of the low voltage conductor 45 is arranged between the second end 41b of the high voltage conductor 41 and the reservoir base 48. This is advantageous because it enables earlier detection of leaked liquid 37, even for a small amount of a predetermined volume of leaked liquid 37, since the leaked liquid 37 flows directly into the interior of the reservoir 47 and is therefore first detected by the low voltage conductor 45, and in the case of further leakage by the high voltage conductor 41. Overall, this advantageous embodiment enables early detection of leakage of a small amount of liquid 37 in the reservoir 47 by the battery management system 38 using the liquid detection system 40. In addition, the second end 41b can be arranged at a higher level outside the reservoir 47, which is closer to the base frame 12b, while the second end 45b of the low voltage conductor 45 can be arranged in the reservoir space 50.

[0064] The reservoir 47 may include at least one optically detectable surface. In other words, the reservoir base 48 or at least a portion of the reservoir wall 49 includes an optically detectable surface or is at least partially transparent. This is advantageous because the detection of liquid 37 that may leak from at least one battery module M1, M2 and M3 can be achieved by a simple optical inspection of at least one optically detectable surface of the reservoir 47. For example, an optical inspection of the tightness of the cooling system 28 or the detection of leaking liquid 37 in the reservoir 47 can be performed in a simple and cost-effective manner using an endoscopic camera. In the case that the optically detectable surface of the reservoir 47 is dry, it can be assumed that the cooling system is sealed or does not have any leaks. In addition, the tray base 35 may include a drain plug (not shown in the figures). It is conceivable that the tray base 35 includes an opening that can be closed by a drain plug and connected to a pump that can be connected to the battery management system 38. In the case that the liquid 37 inside the tray is detected by the battery management system 38, the battery management system 38 can then adjust the opening of the drain plug so that the liquid 37 is sucked out of the tray 33 by the pump. However, one of ordinary skill in the art may employ other mechanisms for removing liquid 37 when liquid 37 is detected inside tray 33 .

[0065] according to Figure 4 and Figures 8 to 10 In the illustrated embodiment, the high voltage conductor 41 is a portion 51 of the bus bar 18. In other words, the bus bar 18 includes a portion adapted in the form of a recessed structure, which may be the lowest point of the corresponding battery module M1, such a portion 51 being configured to serve as the high voltage conductor 41 of the liquid detection system 40. This portion 51 of the bus bar 18 includes a second end 41b, which is the lowest point of the battery module M1, so that in the event of a leak of cooling liquid 29 from at least one of the battery modules M1 and M2, the second end 41b will be the first point of the battery module M1 that will come into contact with the leaked liquid 37. Figure 5 An embodiment is shown, according to which the high voltage conductor 41 is in the form of a sensor wire connected to the bus bar 18, such that a first end 41a of the high voltage conductor 41 is coupled to the bus bar and a second end 41b is disposed between the base frame 12b and the tray base 35, as shown in FIG. Figure 1 and Figure 2 As shown, or the second end 41b is disposed in the reservoir space 50, as shown Figure 3 shown.

[0066] Figure 6 A flow chart of a method S for leak detection inside a battery system 10 according to an embodiment is disclosed.

[0067] The method S comprises a first step S1, which comprises providing a battery system 10, the battery system 10 comprising: a housing 11, comprising a housing frame 12a and a base frame 12b, wherein the housing frame 12a and the base frame 12b surround a housing space 13; a cooling system 28 having a cooling liquid 29; at least one battery module M1, M2 and M3, comprising a plurality of battery cells 14, 15 and 16 electrically connected to each other, wherein the battery modules M1, M2 and M3 are arranged in the housing space 13, wherein the battery modules M1, M2 and M3 are adapted to receive the cooling liquid 29 for cooling; at least one tray 33; a battery management system 38; and a liquid detection system 40. The at least one tray 33 comprises a tray frame 34 and a tray base 35, wherein the tray frame 34 is coupled to the base frame 12b; the tray frame 34 and the tray base 35 are electrically insulated; and the tray base 35 is located at a predetermined distance from the base frame 12b. The liquid detection system 40 is connected to the battery management system 38, wherein the battery management system 38 is adapted to detect the liquid 37 inside the tray 33 through the liquid detection system 40. The liquid detection system 40 comprises a high voltage conductor 41 having a first end 41a connected to the bus bars 18, 19, 20 and 21 and a second end 41b disposed between the base frame 12b and the tray base 35.

[0068] The method S comprises a second step S2 which consists in monitoring a reduction of the cooling liquid 29 inside the cooling system 28 by means of the battery management system 38 .

[0069] The method S comprises a third step S3 consisting in monitoring the increase of the liquid 37 inside the tray 33 by means of the battery management system 38 .

[0070] The method S comprises a fourth step S4 which consists in comparing, by the battery management system 38 , the reduction of the cooling liquid 29 inside the cooling system 28 with the increase of the liquid 37 inside the tray 33 .

[0071] Finally, the method S comprises a fifth step S5 consisting of verifying, by means of the battery management system 38 , that the liquid 37 inside the tray 33 is the cooling liquid 29 if a decrease in the cooling liquid 29 inside the cooling system 28 corresponds to an increase in the liquid 37 inside the tray 33 .

[0072] Figure 7 A flow chart showing a third step S3 of a method S for detecting a liquid 37 inside a battery system 10 according to an embodiment is shown.

[0073] The third step S3 for monitoring the increase of the liquid 37 inside the tray 33 comprises a first sub-step S3a in which the low voltage conductor 45 is switched on when the liquid 37 inside the tray 33 is detected. Figure 8 The first signal 53 shown is sent to the battery management system 38 .

[0074] The third step S3 for monitoring the increase of the liquid 37 inside the tray 33 comprises a second sub-step S3b in which the high voltage conductor 41 is switched on when the liquid 37 inside the tray 33 is detected. Fig. 9 A second signal 54 is shown being sent to the battery management system 38 .

[0075] according to Figures 8 to 10 In the illustrated embodiment, the battery system 10 includes two battery modules M1 and M2 in a housing space 13, each battery module including a plurality of battery cells 14 and 15, respectively. The plurality of battery cells 14 are electrically connected to each other on the upper side of the battery system 10 through a bus bar 20, and the plurality of battery cells 14 are electrically connected to each other on the lower side of the battery system 10 through a bus bar 18. The plurality of battery cells 15 are electrically connected to each other on the upper side of the battery system 10 through a bus bar 21, and the plurality of battery cells 15 are electrically connected to each other on the lower side of the battery system 10 through a bus bar 19. The plurality of battery cells 14 of the battery module M1 are electrically connected to the plurality of battery cells 15 of the battery module M2 through a bus bar 52. The cooling system 28 is configured to provide a cooling liquid 29 to each of the battery modules M1 and M2 along respective paths 30 and 31 to cool the respective battery modules M1 and M2. The battery modules M1 and M2 are adapted to receive a cooling liquid 29 for cooling, so that the cooling liquid 29 can absorb heat energy that can be released by the battery cells 14 and 15 during operation of the battery system 10. The high voltage conductor 41 is part 51 of the bus bar 18. According to the first sub-step S3a of the third step S3 of the method S for monitoring the increase of the liquid 37 inside the tray 33, the low voltage conductor 45 (whose second end 45b is arranged in the reservoir space 50) sends a first signal 53 to the battery management system 38 when the liquid 37 inside the reservoir 47 is detected. Therefore, the low voltage conductor 45 sends a warning signal about the leakage of at least one of the battery modules M1 and M2 to the battery management system 38.

[0076] In the event that the leakage of the cooling liquid 29 further continues from at least one of the battery modules M1 and M2, then the level of the liquid 37 collected in the tray 33 increases, so that at a certain moment, the liquid 37 reaches the second end 41b of the high voltage conductor 41. In other words, the liquid 37 reaches the bus bar 18 of the battery module M1. At this moment, according to the second sub-step S3b of the third step S3 of the method S for monitoring the increase of the liquid 37 inside the tray 33, the high voltage conductor 41 sends the second signal 54 to the battery management system 38 when the liquid 37 inside the tray 33 is detected. Therefore, the battery management system 38 detects the isolation fault. The total amount of cooling liquid 29 in the battery system 10 may be known. Both the low voltage conductor 45 and the high voltage conductor 41 result in the detection of the liquid 37 at different levels inside the tray 33. The leakage level depends on the predetermined distance of the respective second ends 41b and 45b from the tray base 35. If the amount of cooling liquid 29 in the battery system 10 is less than the volume between the locations of the second ends 41 b and 45 b of the respective high-voltage and low-voltage conductors 41 and 45 , electrolysis of the cooling liquid may be considered to have occurred.

[0077] Fig.10 The liquid 37 is shown to reach a higher level, exceeding the position of the module base 25 of the respective battery modules M1 and M2. At such a level of the liquid 37, a large amount of electrolysis may occur, which may result in the generation of explosive gases, which may damage the entire battery system 10. Therefore, early leakage detection of the cooling liquid 29 from at least one of the battery modules M1 and M2 is needed, which can be achieved by the present invention.

[0078] The present invention further discloses a vehicle, which includes at least one battery system 10 and is used for leak detection inside the at least one battery system 10 .

[0079] Reference numerals

[0080] 10. Battery System

[0081] 11. Housing

[0082] 12a Housing frame

[0083] 12b Base frame

[0084] 13 Shell space

[0085] 14 Battery Cells

[0086] 15 Battery Cell

[0087] 16 Battery Cells

[0088] 17 Housing

[0089] 18 Busbar

[0090] 19 Busbar

[0091] 20 Busbar

[0092] 21 Busbar

[0093] 22 Cover assembly

[0094] 23 Positive electrode terminal

[0095] 23' Negative electrode terminal

[0096] 24 Module housing

[0097] 25 Module Base

[0098] 26 Module Space

[0099] 27 Base

[0100] 28 Cooling System

[0101] 29 Cooling liquid

[0102] 30 Path

[0103] 31 Path

[0104] 32 Path

[0105] 33 Pallets

[0106] 34 Pallet Frame

[0107] 35 Pallet Base

[0108] 36 Pallet Space

[0109] 37 Liquid

[0110] 38 Battery Management System

[0111] 39 Microprocessor

[0112] 40 Liquid Detection System

[0113] 41 High voltage conductor

[0114] 41a First end

[0115] 41b Second end

[0116] 42 Resistance Monitoring System

[0117] 43 Electrical conductor

[0118] 44 Electrical conductor

[0119] 45 Low voltage conductor

[0120] 45a First end

[0121] 45b Second end

[0122] 46 Inclined Surface

[0123] 47 Reservoir

[0124] 48 Reservoir Base

[0125] 49 Reservoir wall

[0126] 50 Reservoir space

[0127] 51 parts

[0128] 52 Busbar

[0129] 53 First Signal

[0130] 54 Second Signal

[0131] M1 Battery Module

[0132] M2 Battery Module

[0133] M3 Battery Module

[0134] S method

[0135] S1 First step

[0136] S2 Step 2

[0137] S3 Step 3

[0138] S3a First substep

[0139] S3b Second substep

[0140] S4 Step 4

[0141] S5 Step 5

Claims

1. A battery system comprising: (i) a housing, comprising a housing frame and a base frame, wherein the housing frame and the base frame surround a housing space; (ii) at least one battery module including a plurality of battery cells electrically connected to each other through a bus bar, wherein the battery module is disposed in the housing space; (iii) at least one pallet comprising a pallet frame and a pallet base; as well as (iv) a liquid detection system integrated with a battery management system, wherein the battery management system is adapted to detect conductive liquid inside the tray via the liquid detection system, wherein the liquid detection system comprises a high voltage conductor having a first end connected to the bus bar and a second end disposed between the base frame and the tray base, Wherein the liquid detection system includes a resistance monitoring system configured to monitor the resistance between the high voltage conductor and the tray base.

2. The battery system of claim 1, wherein the liquid detection system further comprises a low voltage conductor having a first end connected to the battery management system and a second end disposed between the second end of the high voltage conductor and the tray base. 3 . The battery system of claim 2 , wherein the resistance monitoring system is configured to monitor the resistance between the low voltage conductor and the tray base. The battery system of claim 1 , wherein the high voltage conductor is part of the bus bar.

5. The battery system of claim 2, wherein the battery management system and the tray are connected to a same ground potential, wherein the battery management system is adapted to detect the conductive liquid between the low voltage conductor and the tray base. The battery system of claim 2 , wherein the tray base includes an inclined surface.

7. The battery system of claim 6, wherein the tray base having the inclined surface comprises at least one liquid reservoir, wherein the battery management system is adapted to detect the conductive liquid inside the liquid reservoir by the liquid detection system.

8. The battery system according to claim 7, wherein the second end of the high voltage conductor and the second end of the low voltage conductor are disposed inside the reservoir, wherein the second end of the low voltage conductor is disposed between the second end of the high voltage conductor and a reservoir base.

9. The battery system of claim 7, wherein the reservoir comprises at least one optically detectable surface.

10. The battery system of claim 7, wherein the reservoir includes a drain plug.

11. A method (S) for leak detection inside a battery system, comprising the following steps: I. (S1) Providing the battery system, including: (i) a housing, comprising a housing frame and a base frame, wherein the housing frame and the base frame surround a housing space; (ii) a cooling system having a cooling liquid; (iii) at least one battery module comprising a plurality of battery cells electrically connected to each other via bus bars, wherein the battery module is disposed in the housing space, wherein the battery module is adapted to receive the cooling liquid for cooling; (iv) at least one pallet comprising a pallet frame and a pallet base; and (v) a liquid detection system integrated with a battery management system, wherein the battery management system is adapted to detect liquid inside the tray via the liquid detection system, wherein the liquid detection system comprises a high voltage conductor having a first end connected to the bus bar and a second end disposed between the base frame and the tray base; II. (S2) monitoring the reduction of the cooling liquid inside the cooling system through the battery management system; III. (S3) monitoring the increase of the liquid inside the tray through the battery management system; IV. (S4) comparing, by the battery management system, a decrease in the cooling liquid within the cooling system with an increase in the liquid within the tray; and V. (S5) Verifying, by the battery management system, that if a decrease in the cooling liquid inside the cooling system corresponds to an increase in the liquid inside the tray, then the liquid inside the tray is the cooling liquid.

12. A method (S) according to claim 11, wherein the step (S3) for monitoring the increase of the liquid inside the tray includes a first sub-step (S3a), in which a low-voltage conductor sends a first signal to the battery management system when the liquid inside the tray is detected.

13. A method (S) according to any one of claims 11 to 12, wherein the step (S3) for monitoring the increase of the liquid inside the tray includes a second sub-step (S3b), in which the high-voltage conductor sends a second signal to the battery management system when the liquid inside the tray is detected.

14. A vehicle comprising at least one battery system according to any one of claims 1 to 10.

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