BATTERY SYSTEM FOR ELECTRIC VEHICLE AND METHOD FOR DETERMINING THERMAL runaway

Abstract

An electric vehicle battery system includes a battery pack including battery cells housed within a housing, and a thermal runaway detection system including a sensor unit to send data and a control unit to receive data therefrom, the sensor unit being positioned within the battery pack and including a first cover element and a second cover element, the second cover element is arranged on / connected to the first cover element to form a space therebetween, the light emitter and the light sensor being arranged within the space such that light emitted from the light emitter can be received at the light sensor via a light path extending across the space, and the first cover element is designed to bend towards the second cover element and into the light path if the pressure in the battery pack increases, the control unit being configured to detect a thermal runaway based on a change in the transmitted data.

Description

Technical Field

[0001] Embodiments relate to a battery system for an electric vehicle, an electric vehicle including the battery system, and a method for determining thermal runaway in the battery system. Background Art

[0002] Recently, vehicles for transporting goods and people have been developed that use electricity as a source of locomotion. Such electric vehicles are cars that are propelled permanently or temporarily by an electric motor using energy stored in a rechargeable battery. Electric vehicles may be powered solely by batteries (battery electric vehicle, BEV), or may include a combination of an electric motor and, for example, a conventional internal combustion engine (plug-in hybrid electric vehicle, PHEV). BEVs and PHEVs use high-capacity rechargeable batteries that are designed to provide power for propulsion over a sustained period of time.

[0003] Typically, a rechargeable (or secondary) battery cell includes an electrode assembly that includes a positive electrode, a negative electrode, and a separator inserted between the electrodes. A solid or liquid electrolyte allows ions to move during charging and discharging of the battery cell. The electrode assembly is located in a housing, and electrode terminals located outside the housing establish a conductive connection with the electrodes. The shape of the housing can be, for example, cylindrical or rectangular.

[0004] A battery module is formed by connecting a plurality of battery cells in series or in parallel. That is, the battery module is formed by interconnecting electrode terminals of a plurality of battery cells depending on the amount of power required, so as to realize a high-power rechargeable battery.

[0005] A battery pack is a group of any number of (e.g., identical) battery modules or individual battery cells. The battery modules of the individual battery cells can be configured in series, in parallel, or a mixture of both to deliver the desired voltage, capacity, and / or power density. The components of a battery pack include individual battery modules and interconnects that provide conductivity between the battery modules.

[0006] The battery system may also include a battery management system (BMS), which is any suitable electronic system configured to manage the rechargeable battery cells, battery modules, and battery packs, such as by protecting the batteries from operating outside of their safe operating range, monitoring their status, calculating secondary data, reporting that data, controlling their environment, authenticating and / or balancing them.

[0007] An active or passive thermal management system may be included to provide thermal control of the battery pack to safely use at least one battery module by effectively emitting, discharging and / or dissipating heat generated from its rechargeable batteries. If heat emission / dissipation / dissipation is not adequately performed, temperature deviations may occur between the corresponding battery cells, so that at least one battery module may no longer generate the desired (or designed) amount of power. In addition, an increase in the internal temperature may cause abnormal reactions to occur therein, and thus the charging and discharging performance of the rechargeable battery deteriorates, and the life of the rechargeable battery is shortened. Therefore, cell cooling for effectively emitting / discharging / dissipating heat from the cells is required.

[0008] The exothermic decomposition of a cell assembly may lead to what is known as thermal runaway. In general, thermal runaway describes a process that is accelerated by a temperature increase and, in turn, releases energy that further increases the temperature. Thermal runaway occurs when a temperature increase changes conditions in a way that causes a further increase in temperature, usually with destructive consequences. In rechargeable battery systems, thermal runaway is associated with a strongly exothermic reaction that is accelerated by a temperature increase. In thermal runaway, the temperature of a battery cell rises incredibly fast and the stored energy is released very suddenly. In extreme cases, thermal runaway may cause a battery cell to explode and catch fire. In lesser cases, it may cause a battery cell to be damaged beyond repair.

[0009] If a battery cell is heated above a critical temperature (e.g., above 150°C), the battery cell may transition into thermal runaway. Typically, temperatures outside the safety zone on the low side or high side may cause irreversible damage to the battery cell and may therefore trigger thermal runaway. Thermal runaway may also occur due to an internal or external short circuit in the battery cell or poor battery maintenance. For example, overcharging or rapid charging may cause thermal runaway.

[0010] During thermal runaway, a faulty battery cell may reach temperatures exceeding 700°C. In addition, large amounts of hot gases are ejected from the inside of the faulty battery cell through the exhaust openings of the cell housing into the battery pack. The main components of the exhausted gases are H2, CO2, CO, electrolyte vapor and other hydrocarbons. Therefore, the exhausted gases are flammable and potentially toxic. The exhausted gases also cause an increase in gas pressure within the battery assembly. In the worst case, the high temperature causes the process to spread to adjacent cells and catch fire in the battery pack. At this stage, the fire is difficult to extinguish.

[0011] If the BMS detects that the temperature is too hot, it can adjust the temperature, for example, by controlling a cooling fan. Alternatively, if the battery cells cannot be cooled and a safe condition is restored, the BMS can shut down the necessary battery cells to protect the entire system.

[0012] To prevent or detect thermal runaway, additional sensor systems for predicting or confirming critical conditions in the battery system may be desirable in addition to known conventional temperature monitoring. Summary of the invention

[0013] Embodiments include a battery system for an electric vehicle. The battery system includes a battery pack and a thermal runaway detection system, the battery pack including a plurality of battery cells housed in a housing, the thermal runaway detection system including a sensor unit and a control unit, the sensor unit being configured to send data to the control unit and the control unit being configured to receive data from the sensor unit, wherein the sensor unit is positioned within the battery pack of the battery system. The sensor unit includes a first cover element and a second cover element, the second cover element being arranged on and connected to the first cover element in a manner that forms a space between the first cover element and the second cover element, a light emitter and a light sensor being arranged within the space so that light emitted from the light emitter can be received at the light sensor via a light path extending across the space, and the first cover element being designed to bend toward the second battery pack and enter the light path if there is a pressure increase in the battery pack, wherein the control unit is configured to detect a possible thermal runaway based on a change in the data sent by the sensor unit.

[0014] The second cover element of the sensor unit can be part of the housing of the battery pack, part of the carrier frame or part of an outer cover seal.

[0015] The control unit can be integrated into a battery management system BMS of the battery system.

[0016] The control unit may be configured to determine a speed and / or height of the pressure increase within the battery pack based on the data sent from the sensor unit and to assess the likelihood of thermal runaway based thereon.

[0017] The light emitter of the sensor unit may be an LED emitting infrared light.

[0018] The light sensor may be a photodiode.

[0019] An electric vehicle including a battery system. The battery system includes a battery pack and a thermal runaway detection system, the battery pack including a plurality of battery cells accommodated in a housing, the thermal runaway detection system including a sensor unit and a control unit, the sensor unit being configured to send data to the control unit and the control unit being configured to receive data from the sensor unit, wherein the sensor unit is positioned within the battery pack of the battery system. The sensor unit includes a first cover element and a second cover element, the second cover element being arranged on and connected to the first cover element in such a way that a space is formed between the first cover element and the second cover element, a light emitter and a light sensor being arranged within the space so that light emitted from the light emitter can be received at the light sensor via a light path extending across the space, and the first cover element being designed to bend toward the second cover element and enter the light path in the event of an increase in pressure in the battery pack, wherein the control unit is configured to detect a possible thermal runaway based on a change in the data sent by the sensor unit.

[0020] The control unit can be integrated into a battery management system BMS of the battery system, and the second cover element of the sensor unit can be part of a housing of the battery pack, part of a carrier frame or part of an outer cover seal.

[0021] The control unit can be configured to determine the rate and / or height of the pressure increase within the battery pack based on the data sent from the sensor unit and to assess the possibility of thermal runaway based on this, and the second cover element of the sensor unit can be part of the housing of the battery pack, part of the carrier frame or part of the outer cover seal.

[0022] The control unit may be configured to determine a rate and / or height of pressure increase within the battery pack based on data sent from the sensor unit and assess the possibility of thermal runaway based thereon, and the control unit may be integrated into a battery management system of the battery system.

[0023] The light emitter of the sensor unit may be an LED emitting infrared light, and the second cover element of the sensor unit may be part of the housing of the battery pack, part of the carrier frame or part of an outer cover seal.

[0024] The light emitter of the sensor unit is an LED emitting infrared light, and the control unit can be integrated into a battery management system of the battery system.

[0025] The light emitter of the sensor unit may be an LED emitting infrared light, and the control unit may be configured to determine the speed and / or height of the pressure increase within the battery pack based on data sent from the sensor unit and based thereon assess the possibility of thermal runaway.

[0026] The light sensor may be a photodiode and the second cover element of the sensor unit may be part of the housing of the battery pack, part of the carrier frame or part of an outer cover seal.

[0027] The light sensor may be a photodiode and the control unit may be integrated into a battery management system of the battery system.

[0028] The light sensor may be a photodiode, and the control unit may be configured to determine the speed and / or height of the pressure increase within the battery pack based on data sent from the sensor unit, and based thereon assess the likelihood of thermal runaway.

[0029] An electric vehicle including a battery system. The battery system includes a battery pack and a thermal runaway detection system, the battery pack including a plurality of battery cells accommodated in a housing, the thermal runaway detection system including a sensor unit and a control unit, the sensor unit being configured to send data to the control unit and the control unit being configured to receive data from the sensor unit, wherein the sensor unit is positioned in the battery pack of the battery system. The sensor unit includes a first cover element and a second cover element, the second cover element being arranged on and connected to the first cover element in a manner of forming a space between the first cover element and the second cover element, a light emitter and a light sensor being arranged in the space so that light emitted from the light emitter can be received at the light sensor via a light path extending across the space, and the first cover element being designed to bend toward the second cover element and enter the light path in the event of an increase in pressure in the battery pack, wherein the control unit is configured to detect a possible thermal runaway based on a change in the data sent by the sensor unit, wherein the second cover element of the sensor unit is a part of the housing of the battery pack, a part of the carrier frame, or a part of the outer cover seal.

[0030] An electric vehicle including a battery system. The battery system includes a battery pack and a thermal runaway detection system, the battery pack including a plurality of battery cells accommodated in a housing, the thermal runaway detection system including a sensor unit and a control unit, the sensor unit and the control unit being configured to send data to the control unit and receive data from the sensor unit, wherein the sensor unit is positioned in the battery pack of the battery system. The sensor unit includes a first cover element and a second cover element, the second cover element being arranged on and connected to the first cover element in a manner of forming a space between the first cover element and the second cover element, a light emitter and a light sensor being arranged in the space so that light emitted from the light emitter can be received at the light sensor via a light path extending across the space, and the first cover element being designed to bend toward the second cover element and enter the light path in the event of an increase in pressure in the battery pack, wherein the control unit is configured to detect a possible thermal runaway based on a change in the data sent by the sensor unit, wherein the control unit is integrated into a battery management system of the battery system.

[0031] Embodiments include a method for determining thermal runaway in a battery system of an electric vehicle. The method includes a) providing a battery system. The battery system includes a battery pack and a thermal runaway detection system, the battery pack including a plurality of battery cells housed in a housing, the thermal runaway detection system including a sensor unit and a control unit, the sensor unit and the control unit being configured to send data to and receive data from the sensor unit, wherein the sensor unit is positioned within the battery pack of the battery system and includes a first cover element and a second cover element, the second cover element being arranged on and connected to the first cover element in a manner that forms a space between the first cover element and the second cover element, a light emitter and a light sensor being arranged within the space so that light emitted from the light emitter can be received at the light sensor via a light path extending across the space, and the first cover element being designed to bend toward the second cover element and enter the light path if pressure in the battery pack increases. The method also includes b) detecting, by the control unit, a possible thermal runaway based on a change in data sent by the sensor unit.

[0032] The control unit may determine the speed and / or height of the pressure increase within the battery pack based on the data sent from the sensor unit and assess the possibility of thermal runaway based thereon. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Features will become apparent to those skilled in the art by describing in detail exemplary embodiments with reference to the accompanying drawings, in which:

[0034] Figure 1 shows a schematic cross-section (block diagram) of a battery system according to one or more embodiments of the present disclosure;

[0035] Figure 2 A sensor unit in a first stage according to one or more embodiments of the present disclosure is shown in a schematic cross-sectional view;

[0036] Figure 3 The second stage according to one or more embodiments of the present disclosure is shown. Figure 2 A sensor unit; and

[0037] Figure 4 A flow chart of a method for determining thermal runaway in a battery system according to one or more embodiments of the present disclosure is shown. DETAILED DESCRIPTION

[0038] Example embodiments will now be described more fully below with reference to the accompanying drawings; however, they may be implemented in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey exemplary implementations to those skilled in the art.

[0039] In the accompanying drawings, the sizes of layers and regions may be exaggerated for clarity of illustration. It should also be understood that if a layer or element is referred to as being "on" another layer or substrate, it can be directly on the other layer or substrate, or there may be intervening layers. In addition, it should be understood that if a layer is referred to as being "below" another layer, it can be directly below, and there may also be one or more intervening layers. In addition, it should also be understood that if a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or there may also be one or more intervening layers.

[0040] Reference will now be made in detail to embodiments, examples of which are shown in the accompanying drawings. The effects and features of the exemplary embodiments and their implementation methods will be described with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals represent the same elements, and redundant descriptions are omitted. However, the present disclosure can be implemented in various different forms and should not be construed as being limited to the embodiments shown herein. On the contrary, these embodiments are provided as examples so that the present disclosure will be thorough and complete, and will fully convey the aspects and features of the present disclosure to those of ordinary skill in the art.

[0041] Therefore, processes, elements, and techniques that are not considered necessary for one of ordinary skill in the art to fully understand the aspects and features of the present disclosure may not be described.

[0042] 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" in the context of describing embodiments of the present disclosure refers to "one or more embodiments of the present disclosure." In the following description of embodiments of the present disclosure, unless the context clearly indicates otherwise, a term in the singular may include a plural form.

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

[0044] Any suitable hardware, firmware (e.g., an application specific integrated circuit), software, or a combination of software, firmware, and hardware may be utilized to implement the electronic or electrical devices and / or any other related devices or components according to the embodiments of the present disclosure described herein. In addition, the various components of these devices may be processes or threads that run on one or more processors in one or more computing devices, execute computer program instructions, and interact with other system components for performing the various functions described herein. The computer program instructions are stored in a memory that may be implemented in a computing device using a standard memory device, such as a random access memory (RAM). The computer program instructions may also be stored in other non-temporary computer-readable media, such as, for example, a CD-ROM, a flash drive, or the like.

[0045] Embodiments relate to a battery system for an electric vehicle. The battery system includes a battery pack, the battery pack including a plurality of battery cells accommodated in a housing. The battery system also includes a thermal runaway detection system, the thermal runaway detection system including a sensor unit and a control unit. The sensor unit is configured to send data to the control unit and the control unit is configured to receive data from the sensor unit. The sensor unit is positioned within the battery pack of the battery system and includes a first cover element and a second cover element, a light emitter and a light sensor, the second cover element being arranged on and connected to the first cover element in a manner forming a space between the first cover element and the second cover element, the light emitter and the light sensor being arranged within the space so that light emitted from the light emitter can be received at the light sensor via a light path extending across the space; and the first cover element is designed to bend toward the second cover element and enter the light path in the event of an increase in pressure in the battery pack (caused by the release of gas in the event of thermal runaway). The control unit is configured to detect a possible thermal runaway based on a change in the data sent by the sensor unit (due to an interruption or reduction in light detected at the light sensor via the light path).

[0046] The gist of the embodiment is a system and method for easily detecting the condition of a battery pack indicating thermal runaway of at least one battery cell. Therefore, the battery system is equipped with a thermal runaway detection system. As stated above, a failure of a battery cell (e.g., a solid or liquid lithium-ion rechargeable battery) used to propel a vehicle may cause thermal runaway. For example, a temperature outside the safety area on the low side or high side may cause irreversible damage to the battery cell and may therefore trigger thermal runaway. Thermal runaway may also occur due to an internal or external short circuit of the battery cell or poor battery maintenance. For example, overcharging or fast charging may cause thermal runaway. Therefore, a large amount of hot gas can be ejected from the inside of the failed battery cell through the exhaust opening of the housing into the battery pack. This process is carried out in a very short time, thereby releasing a considerable amount of gas. However, conventional battery packs only allow controlled gas exchange with the environment in a few places. Therefore, the pressure within the battery pack may rise suddenly. Using the embodiments of this article, such pressure can be detected by a thermal runaway detection system.

[0047] The thermal runaway detection system comprises a sensor unit and a control unit. The sensor unit is configured to send data to the control unit and the control unit is configured to receive data from the sensor unit. Thus, the measurement data recorded by the sensor unit are sent to the control unit. The transmission can be carried out via a data line or wirelessly (e.g. via a WLAN or Bluetooth interface). The communication between the sensor unit and the control unit can be bidirectional and can include further data and control signals. For example, the sensor unit can send information about its operating state at the request of the control unit or send a defect message in the event of a fault.

[0048] The sensor unit is positioned within the battery pack of the battery system. The sensor unit may be mounted inside the battery pack in a manner that immediately detects the pressure increase due to any gas released during thermal runaway, but avoids damage to the sensor unit by the gas. An expert may find a suitable positioning within the battery pack based on the expected distribution pattern of the gas.

[0049] The sensor unit provides a measuring chamber (i.e. the space between the first cover element and the second cover element) which can be shielded and hermetically sealed for optical measurements. One wall of the measuring chamber (i.e. the first cover element) is designed in such a way that the wall can be bent towards the inside of the measuring chamber. The force applied for the mechanical deformation of the wall corresponds to the expected pressure increase in the event of thermal runaway. The first cover element can have elastic properties so that it can return to its original position if the pressure drops. For example, the first cover element can be formed of an elastic polymer or a thin metal sheet.

[0050] On the other hand, the second cover element (or another wall of the measuring chamber) is dimensionally stable to pressure variations inside the battery pack, so that it does not bend in the event of thermal runaway. For example, the second cover element may be formed from a rigid metal sheet.

[0051] According to one or more embodiments, the second cover element of the sensor unit can be part of the housing of the battery pack, part of the carrier frame, or part of the outer cover seal. The housing and support structure of the battery pack can be formed of a solid metal material (e.g., extruded aluminum) to protect the battery cells from huge mechanical impacts in the event of an accident. The housing and support structure can have a flat surface that can be used as the second cover element of the sensor unit. Similarly, a portion of the inner surface of the outer cover can be used as the second cover element. If installed on a vehicle, the outer cover shields the battery pack on the bottom and can also have a pressure-resistant metal wall. In this case, the light emitter, the light sensor, and the first cover element can be easily attached to the provided surface of the assembly. This can be done, for example, using an adhesive.

[0052] In the measuring chamber (or space), a light emitter and a light sensor are placed. The light emitter and the light sensor are aligned with each other in a way that the emitted light can be detected by the light sensor. In the battery pack, the light path spanned by the light is not blocked under normal pressure conditions. As the pressure increases, the first cover element bent into the light path interrupts or reduces the light transmission from the light emitter to the light sensor. The light emitter and the light sensor can be powered via the battery pack or another external energy source (e.g., the electrical system of the vehicle).

[0053] According to one or more embodiments, the light emitter of the sensor unit may be an LED that emits infrared light. Such a light source has proven to be suitable for the application and is also highly cost-effective. The overall height of the LED is also particularly low, so that the overall height of the sensor unit can be kept relatively low.

[0054] According to one or more further embodiments, the light sensor may be a photodiode. Photodiodes are highly cost effective, have a low overall height, and are suitable for intended applications in battery systems.

[0055] The control unit is preferably configured to detect a possible thermal runaway based on a change in the data sent by the sensor unit due to an interruption or reduction of light detected at the light sensor via the light path. The data may be sent continuously, at regular intervals or depending on certain operating states of the battery system. In other words, the control unit evaluates the data sent by the sensor unit.

[0056] According to one or more embodiments, the control unit may be configured to determine the speed and / or height of the pressure increase within the battery pack based on the data sent from the sensor unit, and may also be configured to assess the possibility of thermal runaway based thereon. Details on a corresponding method for determining thermal runaway in a battery system will be provided below.

[0057] According to one or more other embodiments, the control unit may be integrated into a battery management system (BMS) of the battery system. As described above, a BMS is any electronic system that manages battery cells, battery modules and battery packs, such as by protecting the battery cells, battery modules and battery packs from operating outside their safe operating range, monitoring their status, calculating secondary data, reporting this data, controlling their environment, authenticating them and / or balancing them. Therefore, it is a clear advantage to make the knowledge obtained via the control unit available to the BMS and use it to control the battery system.

[0058] Embodiments include a method for determining thermal runaway in a battery system of an electric vehicle. The method includes providing a battery system as described above, and detecting, by a control unit, possible thermal runaway based on changes in sensor data.

[0059] The battery system may further include a thermal runaway detection system including a sensor unit and a control unit, the sensor unit being configured to send data to the control unit and the control unit being configured to receive data from the sensor unit.

[0060] The sensor unit can be positioned within a battery pack of a battery system and can include the following features: a first cover element and a second cover element, the second cover element being arranged on and connected to the first cover element in a manner that forms a space between the first cover element and the second cover element; a light emitter and a light sensor being arranged within the space so that light emitted from the light emitter can be received at the light sensor via a light path extending across the space; and at least the first cover element being designed to bend toward the second cover element and enter the light path when pressure in the battery pack increases.

[0061] The method thus allows detecting a potential thermal runaway in a battery system of an electric vehicle. For example, if the evaluation of the transmitted data shows a significant increase in pressure within the battery pack, the control unit can indicate a potential occurrence of a thermal runaway.

[0062] If the first cover element completely interrupts the light path, the control unit can be configured to directly indicate the presence of thermal runaway. However, if the first cover element only partially blocks the light path due to an increase in internal pressure in the battery pack, the control unit can only indicate the possibility of thermal runaway and initiate a further diagnostic routine. In this case, the control unit can determine, for example, the speed and / or height of the pressure increase within the battery pack based on the data sent from the sensor unit and evaluate the possibility of thermal runaway based on this. For a practical embodiment, a characteristic curve of the pressure increase in the event of thermal runaway can be stored in a memory of the control unit and compared with the course of the pressure sent by the sensor unit. Alternatively or additionally, the control unit can be configured to indicate the possibility of thermal runaway if the change in the data representing the increase in pressure over different time periods exceeds a certain threshold value. The characteristic curve or the threshold value must be defined individually for the respective battery pack.

[0063] Furthermore, the control unit can initiate additional routines (e.g., evaluating temperature data measured in the battery pack) to clarify the safety state of the battery pack. Furthermore, the control unit can initiate countermeasures, such as activating cooling components.

[0064] Exemplary embodiments will now be described with reference to the accompanying drawings.

[0065] Figure 1 is a schematic cross-section in the form of a block diagram of a battery system 100 according to one or more embodiments of the present disclosure. In the depicted example, two battery modules 20a, 20b are housed in a housing 15 of a battery pack 10. Each of the battery modules 20a, 20b may include a plurality of battery cells 30 (e.g., lithium-ion rechargeable battery cells). In adverse circumstances, a single battery cell 30a may switch to a faulty operating state known as thermal runaway, which results in the release of a considerable amount of hot gas in a very short period of time. The gas typically escapes suddenly on the upper side of the battery cell 30a because there is typically a pressure relief valve in the case of the battery cell (the release position is marked with a star). The battery modules 20a, 20b are controlled and monitored by a battery management system BMS 40 and are therefore connected to the battery management system BMS 40 via cable connections 25a, 25b.

[0066] The battery system 100 may also include a thermal runaway detection system 200, which includes a sensor unit 210 and a control unit 250. The sensor unit 210 may be controlled and monitored by the control unit 250 and is connected to the control unit 250 via a cable connection 25c. Thus, measurement data may be sent from the sensor unit 210 to the control unit 250. The communication between the sensor unit 210 and the control unit 250 may be bidirectional and may include additional data and control signals. For example, the sensor unit 210 may send information about its operating state upon request of the control unit 250, or send a defect message in the event of a fault.

[0067] The sensor unit 210 is positioned within the battery pack 10 of the battery system 100. Figure 1 , the sensor unit 210 is mounted inside the battery pack 10 at the inner surface of the housing 15. The positioning of the sensor unit 210 can be selected so that the hot gas released from any defective battery cell 30a does not directly hit the sensor unit 210 to avoid damage. In addition, the positioning can also be selected so that the pressure change inside the battery pack 10 is immediately detected.

[0068] In some embodiments, the control unit 250 may be integrated into the BMS 40. Therefore, data obtained by the control unit 250 from the measurement data of the sensor unit 210 may be directly processed by the BMS 40.

[0069] Figure 2 The sensor unit 210 is shown in a schematic cross-sectional view in a first stage according to one or more embodiments. The sensor unit 210 may be Figure 1 The sensor unit 210 may include a first cover element 212 and a second cover element 214. The second cover element 214 may be arranged on and connected to the first cover element 212 in such a manner that a space 216 is formed between the first cover element 212 and the second cover element 214. The light emitter 220 and the light sensor 230 may be arranged within the space 216 so that the light 240 emitted from the light emitter 220 can be received at the light sensor 230 via a light path extending across the space 216. Figure 2 In the embodiment of the present invention, the light emitter 220 may be an LED that emits infrared light, and the light sensor 230 may be a photodiode that is sensitive to infrared light.

[0070] The first cover element 212 can be designed to bend towards the second cover element 214 and enter the light path when the pressure in the battery pack 10 increases. To ensure functionality, the first cover element 212 can be a film made of an elastomeric material, for example. Preferably, if the pressure inside the battery pack 10 increases, the second cover element 214 does not exhibit elastic behavior. In some embodiments, the second cover element 214 can be part of the housing 15, for example, part of the flat inner surface of the housing 15. It is also conceivable that a part of the carrier frame (not shown) of the battery pack 10 or a part of the outer cover seal (not shown) can form the second cover element 214. In other embodiments, the second cover element 214 can be implemented as an independent structural element of the sensor unit 210.

[0071] If the internal pressure within the battery pack 10 is within the range of normal operation, the sensor unit 210 may be in the first stage. The light 240 emitted by the light emitter 220 may fall on the light sensor 230 in a direct path and unimpeded. A signal corresponding to the amount of received light may be sent from the light sensor 230 to the control unit 250.

[0072] Figure 3 The second stage is shown according to one or more embodiments. Figure 2 Due to the increase in internal pressure within the battery pack 10, the first cover element 212 bends toward the second cover element 214 and blocks the light path. Therefore, the light 240 emitted from the light emitter 220 cannot directly reach the light sensor 230. Therefore, there is a significant change in the measurement data of the light sensor 230 sent to the control unit 250. If the first cover element 212 contacts the second cover element 214, no light 240 falls on the light sensor 230. The increase in internal pressure within the battery pack 10 may be the result of thermal runaway of the failed battery cell 30a.

[0073] The control unit 250 may be configured to detect a possible thermal runaway based on changes in the data sent by the sensor unit 210 .

[0074] Figure 4 A flow chart of a method for determining thermal runaway in a battery system 100 according to one or more embodiments of the present disclosure is shown.

[0075] In a first step S1 of the method, a battery system 100 as described in the previous section is provided.

[0076] In a second step S2, the amount of light 240 received at the light sensor 230 may be measured in the sensor unit 210, for example, the measurement may be continuous. The measured data may then be sent to the control unit 250. The data may be sent continuously, at regular intervals or depending on certain operating states of the battery system 100.

[0077] In step S3, detecting a possible thermal runaway may be performed by the control unit 250 based on a change in the data sent by the sensor unit 210. If the control unit 250 detects no data change, there may be no thermal runaway. However, if the first cover element 212 completely interrupts the light path, the control unit 250 may directly indicate the presence of thermal runaway.

[0078] In the case where the light path is only partially blocked by the curved first cover element 212 (e.g. Figure 3 ), the control unit 250 may evaluate the speed and / or height of the pressure increase within the battery pack 10 based on the data transmitted from the sensor unit 210, and may evaluate the possibility of thermal runaway based on this. In some embodiments, a characteristic curve of the pressure increase in the event of thermal runaway may be stored in the memory of the control unit 250. The stored characteristic curve may be compared with the course of the pressure sent by the sensor unit 210. If the course of the curves is the same, the control unit 250 may indicate the possibility of thermal runaway.

[0079] In step S4, the control unit 250 generates a corresponding status message to the BMS 40. The BMS 40 may initiate additional routines (e.g., evaluation of temperature data measured in the battery pack 10) to clarify the safety state of the battery pack 10. In addition, the BMS 40 may initiate countermeasures, for example, activation of cooling elements. Further safety measures may also be initiated by the BMS 40. For example, the vehicle may be automatically stopped, a cooling system and / or a fire extinguishing system may be activated. In addition, a warning signal may be triggered inside the passenger compartment of the vehicle.

[0080] In an embodiment, the BMS may monitor the state of the battery cells, which is represented by voltage (e.g., the total voltage of the battery pack or battery module and / or the voltage of an individual battery cell), temperature (e.g., the average temperature of the battery pack or battery module, the coolant inlet (intake) temperature, the coolant output temperature, or the temperature of an individual battery cell), coolant flow (e.g., flow rate and / or cooling liquid pressure), and current. In addition, the BMS may calculate values ​​based on the above parameters, such as minimum and maximum cell voltages, state of charge (SOC) or depth of discharge (DOD) indicating the charge level of the battery cell, state of health (SOH; differently defined measurements of the remaining capacity of the battery cell, expressed as a percentage (%) of the original capacity), state of power (SOP; the power available for a defined time interval given the current power usage, temperature, and other conditions), state of safety (SOS), maximum charge current as a charge current limit (CCL), maximum discharge current as a discharge current limit (DCL), and internal impedance of the cell (to determine the open circuit voltage).

[0081] In some embodiments, the BMS may be centralized, with a single controller connected to the battery cells via multiple leads. In other embodiments, the BMS may be distributed, with a BMS board mounted at each cell with only a single communication cable between the battery cell and the controller. In other embodiments, the BMS may have a modular construction including several controllers, each handling a certain number of cells while communicating between the controllers. Centralized BMS are the most economical, but have the least scalability and suffer from a large number of leads. Distributed BMS are the most expensive, but are the simplest to install and supply the cleanest components. Modular BMS offers a compromise between the features and problems of the other two topologies.

[0082] The BMS can protect the battery pack from operating outside its safe operating range. Operation outside the safe operating range can be indicated by overcurrent, overvoltage (during charging), overtemperature, undertemperature, overvoltage, and ground fault or leakage current detection. The BMS can prevent the battery from operating outside its safe operating parameters by including an internal switch (e.g., a relay or solid-state device) that disconnects if the battery operates outside its safe operating parameters, thereby requesting devices connected to the battery to reduce or even terminate use of the battery, and actively controlling the environment, such as through heaters, fans, air conditioning, or liquid cooling.

[0083] Example embodiments have been disclosed herein, and although specific terms are employed, they are used and interpreted in a general and descriptive sense only and not for purposes of limitation. In some cases, as will be apparent to one of ordinary skill in the art at the time of filing this application, unless otherwise specifically stated, features, characteristics, and / or elements described in conjunction with a particular embodiment may be used alone or in combination with features, characteristics, and / or elements described in conjunction with other embodiments. Therefore, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

[0084] [reference numerals]

[0085] 10. Battery Pack

[0086] 15 Housing

[0087] 20a, 20b battery module

[0088] 25a, 25b, 25c cable connection

[0089] 30 battery cells

[0090] 30a Defective battery cell

[0091] 40 Battery Management System

[0092] 100 Battery System

[0093] 200 Thermal runaway detection system

[0094] 210 Sensor unit

[0095] 212 first cover element

[0096] 214 second cover element

[0097] 216 Space

[0098] 220 Optical Transmitter

[0099] 230 Light Sensor

[0100] 240 Light

Claims

1. A battery system for an electric vehicle, the battery system comprising: A battery pack, comprising a plurality of battery cells housed in a housing and a thermal runaway detection system, the thermal runaway detection system comprising a sensor unit and a control unit, the sensor unit being configured to send data to the control unit and the control unit being configured to receive data from the sensor unit, wherein the sensor unit is positioned within the battery pack of the battery system and comprises: a first cover element and a second cover element, the second cover element being arranged on the first cover element and connected to the first cover element in such a way that a space is formed between the first cover element and the second cover element; a light emitter and a light sensor arranged within the space such that light emitted from the light emitter can be received at the light sensor via a light path extending across the space; and the first cover element being designed to bend towards the second cover element and into the light path if pressure in the battery pack increases; and Therein, the control unit is configured to detect a possible thermal runaway based on a change in data sent by the sensor unit.

2. The battery system according to claim 1, wherein: The second cover element of the sensor unit is part of the housing of the battery pack, part of a carrier frame or part of an outer cover seal.

3. The battery system according to claim 1, wherein: The control unit is integrated into a battery management system of the battery system.

4. The battery system according to claim 1, wherein: The control unit is configured to determine a speed and / or a height of the pressure increase within the battery pack based on the data sent from the sensor unit, and to assess a possibility of thermal runaway based on the speed and / or the height of the pressure increase.

5. The battery system according to claim 1, wherein: The light emitter of the sensor unit is an LED that emits infrared light.

6. The battery system according to claim 1, wherein: The light sensor is a photodiode.

7. An electric vehicle comprising the battery system according to any one of claims 1 to 6.

8. A method for determining thermal runaway in a battery system of an electric vehicle, wherein: The method comprises the following steps: a) providing a battery system, the battery system comprising: A battery pack including a plurality of battery cells accommodated in a housing; and A thermal runaway detection system, comprising a sensor unit and a control unit, the sensor unit being configured to send data to the control unit and the control unit being configured to receive data from the sensor unit, Wherein, the sensor unit is positioned in the battery pack of the battery system and comprises: a first cover element and a second cover element, the second cover element being arranged on the first cover element and connected to the first cover element in such a way that a space is formed between the first cover element and the second cover element; a light emitter and a light sensor arranged within the space such that light emitted from the light emitter can be received at the light sensor via a light path extending across the space; and the first cover element being designed to bend towards the second cover element and into the light path if pressure in the battery pack increases; and b) Detecting a possible thermal runaway by the control unit based on changes in the data sent by the sensor unit.

9. The method according to claim 8, wherein: The control unit determines a speed and / or a height of the pressure increase within the battery pack based on the data transmitted from the sensor unit, and evaluates a possibility of thermal runaway based on the speed and / or the height of the pressure increase.

Images