Battery system and method for avoiding gas combustion in a battery system

Abstract

The present invention provides a battery system and a method for avoiding gas combustion in a battery system, wherein the battery system comprises: a battery pack comprising a housing and a plurality of battery cells accommodated in the housing; an inert gas generating unit configured to provide inert gas and flush the housing with the inert gas; a battery management system configured to detect an abnormal condition that can cause the battery pack to undergo thermal runaway, and further configured to activate the inert gas generating unit when the abnormal condition is detected by the battery management system; and a temperature sensor configured to measure a temperature in the housing and provide measurement data to the battery management system.

Description

Technical Field

[0001] This disclosure relates to a battery system and a method for preventing combustion of gases in the battery system. This disclosure also relates to an electric vehicle that includes the battery system. Background Technology

[0002] In recent years, vehicles using electricity as a power source for transporting goods and people have been developed. Such electric vehicles are automobiles driven by electric motors, using energy stored in rechargeable batteries. Electric vehicles can be powered solely by batteries, or they can be hybrid vehicles powered by, for example, gasoline generators or hydrogen fuel cells. Furthermore, vehicles can include a combination of electric motors and conventional internal combustion engines. Generally, electric vehicle batteries (EVBs), or traction batteries, are batteries used to power battery electric vehicles (BEVs). Electric vehicle batteries differ from starter batteries, lighting batteries, and ignition batteries because they are designed to provide continuous power. Rechargeable batteries, or secondary batteries, differ from primary batteries in that they can be repeatedly charged and discharged, while primary batteries only provide the irreversible conversion of chemical energy into electrical energy. Low-capacity rechargeable batteries are used as power sources for small electronic devices such as mobile phones, laptops, and cameras, while high-capacity rechargeable batteries are used as power sources for electric and hybrid vehicles.

[0003] Typically, a rechargeable battery includes an electrode assembly, a housing containing the electrode assembly, and electrode terminals electrically connected to the electrodes of the electrode assembly, which includes a positive electrode, a negative electrode, and a separator inserted between the positive and negative electrodes. An electrolyte solution is injected into the housing to enable charging and discharging. 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 application in laptops and consumer electronics, dominate a newly developed group of electric vehicles.

[0004] Rechargeable batteries can be used as battery modules formed by multiple unit battery cells connected in series and / or parallel to provide high energy capacity, particularly for electric motor propulsion in vehicles. That is, battery modules are formed by interconnecting the electrode terminals of multiple unit battery cells, depending on the required power and in order to achieve a high-power rechargeable battery.

[0005] Battery modules can be constructed in a block design or a modular design. In a block design, each battery cell is connected to a common current collector structure and arranged in a housing. In a modular design, multiple battery cells are connected to form submodules, and several submodules are connected to form a battery module. In automotive applications, battery systems typically consist of multiple battery modules connected in series to provide a desired voltage. A battery module may include submodules with multiple stacked battery cells, each stack comprising multiple battery cells connected in parallel (XpYs) or multiple battery cells connected in series (XsYp) in parallel.

[0006] A battery pack is a group of any number (preferably identical) battery modules. They can be configured in series, parallel, or a combination of both to provide the required voltage, capacity, or power density. The components of a battery pack include the individual battery modules and the interconnections that provide conductivity between them.

[0007] The battery system also includes a battery management system (BMS), which is any electronic system that manages rechargeable battery cells, battery modules, and battery packs by protecting battery cells from operating outside their safe operating areas, monitoring their status, calculating secondary data, reporting that data, controlling their environment, certifying them, and / or balancing them. For example, a BMS can monitor the status of a battery pack, battery module, or battery cell, as expressed by voltage (such as the total voltage of the battery pack or battery module, or the voltage of the individual cells), temperature (such as the average temperature of the battery pack or battery module, the coolant inlet temperature, the coolant outlet temperature, or the temperature of the individual cells), coolant flow (such as flow rate, coolant pressure), and current. In addition, the BMS can calculate values ​​based on the above items, such as minimum and maximum cell voltage, state of charge (SOC) or depth of discharge (DOD) to indicate the battery's charge level, state of health (SOH; a measurement of the battery's remaining capacity as a percentage of its original capacity, defined in various ways), state of power (SOP; the amount of power available over a defined time interval given current power usage, temperature, and other conditions), state of safety (SOS), maximum charging current as charge current limit (CCL), maximum discharging current as discharge current limit (DCL), and the cell's internal impedance (to determine the open-circuit voltage).

[0008] A Battery Management System (BMS) can be centralized, where a single controller is connected to the battery cells via multiple wires. A BMS can also be distributed, where the BMS board is installed at each cell, with only one communication cable between the battery and the controller. Alternatively, a BMS can be a modular construction comprising several controllers, each handling a certain number of cells and communicating with each other. Centralized BMSs are the most economical, but the least scalable, and are plagued by a large number of wires. Distributed BMSs are the most expensive, the simplest to install, and offer the cleanest components. Modular BMSs offer a trade-off between the characteristics and problems of the other two topologies.

[0009] A Battery Management System (BMS) protects the battery pack from operating outside its safe operating area. Operation outside the safe operating area can be indicated in the event of overcurrent, overvoltage (during charging), overtemperature, undertemperature, overpressure, ground faults, or leakage current detection. The BMS can prevent operation outside the battery's safe operating area by including internal switches (such as relays or solid-state devices) that open if the battery operates outside its safe operating area, devices requesting connection to the battery to reduce or even terminate battery use, and active environmental control (such as through heaters, fans, air conditioning, or liquid cooling).

[0010] Specifically, when a cell fault is detected, the BMS will take necessary measures. For example, electrolyte breakdown may lead to the release of flammable gases. The BMS can then activate the circuit interrupter (CID), which initiates current cutoff. In the case of cathode breakdown, oxygen is released, and the BMS can open the pressure vent.

[0011] However, oxidation of cell components can lead to so-called thermal runaway, at which point the BMS (Battery Management System) often intervenes too late, resulting in cell destruction. Thermal runaway typically describes a process accelerated by rising temperatures, releasing energy to further increase the temperature. It occurs when altered conditions cause temperatures to rise further, usually leading to destructive consequences. In rechargeable battery systems, thermal runaway is associated with intense exothermic reactions that are accelerated by rising temperatures. These exothermic reactions include the combustion of combustible gas components within the battery pack casing. For example, a cell can transition to thermal runaway when heated above a critical temperature (typically above 150°C). Initial heating may be caused by localized faults, such as internal short circuits, heat generation from defective electrical contacts, or short circuits with adjacent cells. During thermal runaway, the faulty cell (i.e., the cell with localized faults) can reach temperatures exceeding 700°C. Furthermore, large amounts of hot gases are ejected from the interior of the faulty cell into the battery pack through vents in the cell casing. The main components of the expelled gases are H2, CO2, CO, electrolyte vapor, and other hydrocarbons. Therefore, the emitted gases are flammable and potentially toxic. The emitted gases also cause an increase in pressure inside the battery pack. Therefore, the battery pack housing typically includes a venting assembly to prevent excessive overpressure. The venting assembly (e.g., an explosion-proof panel) opens and releases the gas mixture into the environment.

[0012] At the start of unit exhaust, a combustible gas mixture remains within the battery pack housing as long as the exhaust gas does not completely displace all the air outside through the exhaust assembly. If all the air is displaced by the hot exhaust gas, deflagration is impossible. However, if the exhaust gas inside the battery pack cools down and air is drawn back into the battery pack housing from the environment, a combustible gas mixture may form again.

[0013] Detonation can occur as long as a flammable fuel-air mixture is present inside the battery casing. Detonation causes a high pressure spike, which can damage the battery casing. A damaged battery casing allows air to enter hot components inside the damaged battery pack. These hot components can ignite, eventually causing the entire battery to catch fire.

[0014] One object of this disclosure is to overcome or reduce at least some of the disadvantages of the prior art and to provide a battery system that reduces or may eliminate the risk associated with the generation of flammable gas components inside the battery pack. Summary of the Invention

[0015] This invention is defined by the appended claims. The following description is subject to this limitation.

[0016] According to one aspect of this disclosure, a battery system is provided, wherein the battery system includes: a battery pack including a housing and a plurality of battery cells housed within the housing; an inert gas generating unit configured to provide inert gas and flush the housing with inert gas; a battery management system configured to detect an abnormal condition that may cause thermal runaway of the battery pack, and further configured to activate the inert gas generating unit when the abnormal condition is detected by the battery management system; and a temperature sensor configured to measure the temperature within the housing and provide measurement data to the battery management system.

[0017] According to another aspect of this disclosure, a vehicle is provided that includes the battery system described above.

[0018] According to another aspect of this disclosure, a method for preventing gas combustion in a battery system is provided, wherein the method includes the following steps: a) providing a battery system, the battery system including: a battery pack, including a housing and a plurality of battery cells housed within the housing; an inert gas generating unit configured to generate inert gas and flush the housing with the inert gas; a battery management system configured to detect an abnormal condition that may cause thermal runaway of the battery pack, and further configured to activate the inert gas generating unit when the abnormal condition is detected by the battery management system; and a temperature sensor configured to measure the temperature inside the housing and provide measurement data to the battery management system; b) detecting the abnormal condition and generating a first activation signal by the battery management system, and sending the first activation signal to the inert gas generating unit by the battery management system; and c) generating inert gas by the inert gas generating unit and flushing the housing with the inert gas after receiving the first activation signal from the battery management system.

[0019] Further aspects of this disclosure may be learned from the dependent claims or the following description. Attached Figure Description

[0020] Features will become apparent to those skilled in the art from the detailed description of exemplary embodiments with reference to the accompanying drawings, in which:

[0021] Figure 1 This is a top view showing a battery system according to a first embodiment of the present disclosure.

[0022] Figure 2 This is a top view showing a battery system according to a second embodiment of the present disclosure.

[0023] Figure 3 This is a flowchart illustrating a method for preventing gas combustion in the battery systems of the first and second embodiments.

[0024] Figure Labels

[0025] 1 Battery System

[0026] 10 battery packs

[0027] 11. Shell

[0028] 12 Battery Modules

[0029] 13, 13.2 Inert Gas Generation Unit

[0030] 13a First Gas Generator

[0031] 13b Second Gas Generator

[0032] 14 Battery Management System

[0033] 15 Exhaust Assembly

[0034] 16 Temperature Sensors Detailed Implementation

[0035] Description of embodiments will now be given in detail, examples of which are illustrated in the accompanying drawings. The effects and features of exemplary embodiments and methods of implementation thereof will be described with reference to the drawings. However, this disclosure may be implemented in a variety of different forms and should not be construed as limited to the embodiments shown herein. Rather, these embodiments are provided as examples so that this disclosure will be thorough and complete and will fully convey to those skilled in the art aspects and features of this disclosure.

[0036] Therefore, processes, elements, and techniques that are not considered essential for a person skilled in the art to fully understand the aspects and features of this disclosure are not described. In the accompanying drawings, the relative dimensions of elements, layers, and regions may be exaggerated for clarity.

[0037] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items. Furthermore, when describing embodiments of this disclosure, the use of “may” refers to “one or more embodiments of this disclosure”.

[0038] The electronic or electrical devices and / or any other related devices or components according to embodiments of this disclosure described herein can be implemented using any suitable hardware, firmware (e.g., application-specific integrated circuits), software, or a combination of software, firmware, and hardware. Furthermore, various components of these devices can be implemented on flexible printed circuit films, tape-on-a-carrier packages (TCPs), printed circuit boards (PCBs), or formed on a substrate. The electrical connections or interconnections described herein can be implemented, for example, by wires or conductive elements on a PCB or another circuit carrier. Conductive elements may include metallization, such as surface metallization, and / or pins, and / or may include conductive polymers or ceramics. Furthermore, electrical energy can be transmitted wirelessly, for example using electromagnetic radiation and / or light.

[0039] Furthermore, the various components of these devices can be processes or threads running on one or more processors in one or more computing devices, executing computer program instructions and interacting with other system components for performing the various functions described herein. The computer program instructions are stored in memory, which can be implemented in a computing device using standard storage devices, such as, for example, random access memory (RAM). The computer program instructions can also be stored in other non-transitory computer-readable media, such as, for example, CD-ROMs, flash drives, etc.

[0040] Furthermore, those skilled in the art will recognize that, without departing from the scope of the exemplary embodiments of this disclosure, the functions of various computing devices may be combined or integrated into a single computing device, or the functions of a particular computing device may be distributed across one or more other computing devices.

[0041] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will also be understood that terms (such as those defined in common dictionaries) shall be interpreted as having a meaning consistent with their meaning in the context of the relevant field and / or in this specification, and shall not be interpreted as having an idealized or overly formal meaning, unless expressly stated herein.

[0042] General Concepts

[0043] According to one aspect of this disclosure, an improved battery system is provided. The battery system includes a battery pack comprising a housing and a plurality of battery cells housed within the housing. The battery system further includes an inert gas generating unit configured to provide and flush the housing with inert gas. The battery system also includes a battery management system (BMS) configured to detect abnormal conditions that could cause thermal runaway of the battery pack, and further configured to activate the inert gas generating unit when the abnormal condition is detected by the BMS.

[0044] In other words, the battery system includes an inert gas generation unit that is activated when the BMS detects a condition that could lead to thermal runaway. In response to the BMS's activation signal, the inert gas generation unit immediately (i.e., within seconds, particularly less than 2 seconds) flushes the battery pack housing with inert gas. The inert gas is generated by the inert gas generation unit. The inert gas is dispersed into the battery pack housing and displaces the gas mixture located there. Simultaneously, the BMS can open the pressure vent of the venting assembly to release the gas mixture. Therefore, even before the situation spirals out of control, i.e., before thermal runaway has begun, the BMS activates the inert gas generation unit to flush the battery pack housing with inert gas. On the one hand, this measure reduces the risk of thermal runaway because the combustible gas mixture is diluted, displaced, and released. On the other hand, thermal runaway can still be suppressed, and the high-heat-release process can be prevented from spreading to adjacent battery cells or battery modules.

[0045] In the sense of this disclosure, an inert gas is a gaseous compound that does not react with compounds present during combustion. Specifically, an inert gas does not react with oxygen or combustible gases present in the battery pack during or prior to thermal runaway. Suitable inert gases may include, for example, nitrogen, carbon dioxide, and argon.

[0046] The inert gas generating unit is configured to flush inert gas into the battery pack housing. If the inert gas generating unit is assembled inside the battery pack housing, the inert gas can be simply blown into the interior of the housing. If the inert gas generating unit is assembled close to the battery pack housing, the inert gas generating unit will include guiding elements for the generated inert gas, such as a guide plate or conduit extending into the interior of the housing.

[0047] According to one embodiment, the inert gas generating unit may include a first inert gas generator configured to be activated upon detection of an abnormal condition, generating inert gas and flushing the housing with the inert gas. Typically, a gas generator is a device for producing gas. When storing pressurized gas is undesirable or impractical, the gas generator can generate gas through a chemical reaction or from a solid or liquid source. The first inert gas generator preferably generates the inert gas through a chemical reaction. For example, automotive airbags use sodium azide for inflation. A small pyrotechnic charge triggers its decomposition, producing nitrogen, which inflates the airbag within milliseconds. Similar gas generators are used for fire suppression. Therefore, the first inert gas generator can also generate the inert gas, i.e., nitrogen, through the exothermic decomposition of sodium azide.

[0048] According to another embodiment (which may also include the aforementioned first inert gas generator), the BMS can also be configured to detect thermal runaway and activate the inert gas generation unit when the BMS has detected thermal runaway. Therefore, the inert gas generation unit can be activated a second time, causing a second flush of inert gas into the interior of the housing. This measure not only suppresses the rapid propagation of the thermal runaway location but also prevents the battery system from drawing in fresh air from its surroundings.

[0049] The inert gas generation unit may specifically include a second inert gas generator configured to be activated upon detection of thermal runaway, generating and flushing the housing with inert gas. Therefore, the battery system may include at least two inert gas generators activated under different operating conditions detected by the BMS. For example, a first inert gas generator will be activated when an abnormal condition that could lead to thermal runaway is detected. If thermal runaway still occurs, or even if no abnormal condition is detected and the first inert gas generator is not activated, at least the second inert gas generator will flush the housing with inert gas.

[0050] The first and / or second inert gas generators can be pyrotechnic inert gas generators. As described above, the pyrotechnic charge triggers the decomposition of the inert gas-generating compound (such as azides, particularly sodium azide). The pyrotechnic inert gas generator has a very short response time, meaning it begins generating inert gas almost immediately after receiving the BMS activation signal.

[0051] Specifically, the first gas generator can be configured to generate gas between 0.1 and 5 seconds. This is typically sufficient to completely submerge the battery pack casing of the electric vehicle, i.e., to completely flush the casing with inert gas. The second gas generator can be configured to generate gas between 0.1 and 20 seconds. Therefore, the generation of inert gas can continue for a slightly longer period to prevent reignition in the event of thermal runaway.

[0052] Abnormal conditions that could lead to thermal runaway can be indicated.

[0053] The detection of abnormal conditions may include (i) a BMS subroutine for calculating the probability of thermal runaway and / or (ii) controlling at least one parameter of the battery system. For example, the following events may indicate an abnormal condition:

[0054] • Exceeding the temperature limit inside the casing or on the surface of the battery cell;

[0055] Collision detected;

[0056] • An abnormal voltage was detected in one or more battery cells;

[0057] • Overcurrent was detected in the battery pack; and

[0058] • An unusual gas composition was detected inside the casing.

[0059] The appropriate parameters used to determine abnormal conditions depend on the specific configuration of the battery system and need to be adjusted for the specific application. For example, the battery cell temperature can be measured directly at the surface of the battery cell housing. If the temperature exceeds 100°C, the BMS will activate the inert gas generation unit. Alternatively, a collision sensor can detect a collision between the vehicle containing the battery system and another object. The detected collision can cause the BMS to activate the inert gas generation unit. Furthermore, a detected abnormal voltage in a battery cell or an overcurrent in the battery pack can activate the BMS to activate the inert gas generation unit. Additionally, gas sensors within the battery pack housing can detect abnormal gas components indicating damage to the battery cells.

[0060] In addition to controlling one or more specified parameters, the BMS may optionally include or additionally include an algorithm for determining the Safety State of Operation (SOS) (e.g., see E. Cabrera-Castillo et al., Power Supply Journal, Vol. 324, pp. 509-520). The SOS can calculate the probability level of battery system failure. Therefore, exceeding a given probability level can indicate an abnormal condition, and thus the BMS can set a first activation signal for the inert gas generation unit. In other words, the BMS is configured to control the activity of the inert gas generation unit using the SOS subroutine. Other subroutines for indicating the probability of thermal runaway (i.e., an abnormal condition) can also be implemented in the BMS. Typically, the BMS is configured to detect abnormal conditions that could lead to thermal runaway.

[0061] In a very similar manner, the detection of thermal runaway may include (i) a BMS subroutine for calculating thermal runaway and / or (ii) at least one parameter controlling the battery system. For example, the following events can indicate thermal runaway:

[0062] • Exceeding the temperature limit inside the casing or at the surface of the battery cell; and

[0063] • An unusual gas composition was detected inside the casing.

[0064] In addition to these parameters, a BMS can also include subroutines that indicate thermal runaway. Typically, a BMS is configured to detect thermal runaway.

[0065] In addition, the battery pack can be airtight, preferably in addition to a filter that allows gas exchange to the environment to compensate for pressure changes due to temperature or altitude variations.

[0066] The advantage of this battery system is that, in the event of a cell failure, the emission of the combustible gas mixture can be carried out in a more controlled manner, preventing or at least reducing damage to a part or the entire battery system or to people in the vicinity.

[0067] According to another aspect of this disclosure, the vehicle (particularly an electric vehicle) includes a battery system as described in any of the foregoing embodiments. One advantage of such a vehicle is improved safety for the driver and passengers. Furthermore, it reduces damage to the vehicle caused by thermal runaway of the battery system.

[0068] According to another aspect of this disclosure, a method for preventing gas combustion in a battery system is provided, wherein the method includes the following steps:

[0069] a) Provide a battery system, the battery system including

[0070] A battery pack, including a housing and multiple battery cells housed within the housing;

[0071] An inert gas generating unit is configured to generate inert gas and flush the housing with the inert gas; and

[0072] The battery management system (BMS) is configured to detect abnormal conditions that may cause thermal runaway of the battery pack, and is also configured to activate the inert gas generation unit when the abnormal condition is detected by the BMS.

[0073] b) Detect abnormal conditions using the BMS and generate a first activation signal, then send the first activation signal to the inert gas generation unit via the BMS; and

[0074] c) After receiving the first activation signal from the BMS, inert gas is generated by the inert gas generating unit and the housing is flushed with the inert gas.

[0075] Further details of the battery system, including the inert gas generation unit, are provided above.

[0076] The inert gas generating unit may include a first inert gas generator configured to be activated and generate inert gas when an abnormal condition is detected, and wherein in step c), the first inert gas generator may generate inert gas and flush the housing with inert gas in response to a first activation signal from the BMS.

[0077] The BMS can be further configured to also detect thermal runaway, and activate the inert gas generation unit when the BMS has detected thermal runaway. Therefore, the method may further include the following steps:

[0078] d) By detecting thermal runaway and generating a second activation signal through the BMS, the second activation signal is sent to the inert gas generation unit via the BMS; and

[0079] e) After receiving the second activation signal from the BMS, inert gas is generated by the inert gas generating unit and the housing is flushed with the inert gas.

[0080] The inert gas generating unit may include a second inert gas generator configured to be activated and generate inert gas when thermal runaway is detected, and wherein in step e), the second inert gas generator may generate inert gas and flush the housing with inert gas in response to a second activation signal from the BMS.

[0081] In step b), the abnormal conditions that could lead to thermal runaway can be determined by: (i) the BMS subroutine used to calculate the probability of thermal runaway and / or (ii) selected parameters controlling the battery system. Exemplary BMS subroutines and suitable parameters for determination have been described above.

[0082] In step d), thermal runaway detection can be determined by: (i) the BMS subroutine used to calculate thermal runaway and / or (ii) selected parameters controlling the battery system. Exemplary BMS subroutines and suitable parameters for determination have been described above.

[0083] Exemplary implementation method

[0084] As a first exemplary implementation method, Figure 1 A battery system 1 including a battery pack 10 is shown, the battery pack 10 comprising a housing 11 and a plurality of battery modules 12 housed within the housing 11. The battery system 1 can be formed as part of, for example, a propulsion component of an electric vehicle. Each battery module 12 includes a plurality of battery cells connected in series and / or in parallel to provide high energy capacity for the vehicle's electric motor drive. That is, each battery module 12 is formed by interconnecting the electrode terminals of a plurality of individual battery cells according to the required power, in order to achieve a high-power rechargeable battery pack 10. Furthermore, the battery modules 12 can be constructed in a block design or a modular design. For clarity, and because these details are not essential for understanding this disclosure, the high-voltage lines, individual battery cells, and other high-voltage components of the battery modules 12 of the battery pack 10 are not shown in the figures.

[0085] Battery system 1 also includes a battery management system (BMS) 14. According to an exemplary embodiment, BMS 14 is centralized, such that a single controller is connected to the battery cells of battery module 12 via multiple wires. Figure 1 (The signal lines from BMS14 to battery module 12 are shown schematically.) Here, BMS14 is assembled inside the housing 11 of battery pack 10, but it can also be located outside the housing 11.

[0086] BMS 14 is any electronic system that manages rechargeable batteries and battery modules 12 by means of protecting batteries from operating outside their safe operating areas, monitoring their status, calculating secondary data, reporting that data, controlling their environment, certifying them, and / or balancing them. For example, BMS 14 can monitor battery status as expressed by voltage (such as the total voltage of the battery pack or battery module, the voltage of individual cells), temperature (such as the average temperature of the battery pack or battery module, the coolant inlet temperature, the coolant outlet temperature, or the temperature of individual cells), coolant flow (such as flow rate, coolant pressure), and current. Additionally, BMS 14 can calculate values ​​based on the above items, such as minimum and maximum cell voltages, state of charge (SOC) or depth of discharge (DOD) to indicate the battery's charge level, state of health (SOH; a measurement of the battery's remaining capacity as a percentage of its original capacity, defined in various ways), state of power (SOP; the amount of power available over a defined time interval given current power usage, temperature, and other conditions), state of safety (SOS), maximum charging current as charge current limit (CCL), maximum discharging current as discharge current limit (DCL), and the cell's internal impedance (to determine the open-circuit voltage). To simplify the functionality of BMS 14, the exemplary embodiment shows only a single temperature sensor 16, which measures the temperature within the housing 11 and provides measurement data to BMS 14. However, other sensed parameters or calculated values ​​can also be adapted to determine the occurrence of thermal runaway or thermal runaway itself.

[0087] Furthermore, an inert gas generating unit 13 is assembled within the housing 11 of the battery pack 10. The inert gas generating unit 13 is configured to generate inert gas and flush the housing 11 with the inert gas. According to an exemplary embodiment, the inert gas generating unit 13 is connected to the BMS 14 via a signal line. The inert gas generating unit 13 may include or even consist of a pyrotechnic inert gas generator, which generates inert gas through a chemical reaction. For example, the inert gas generator can generate nitrogen as an inert gas from the exothermic decomposition of sodium azide.

[0088] Figure 1 An exhaust assembly 15 is also shown, which can also be controlled by the BMS 14. Such an exhaust assembly 15 may include a switchable valve and a filtration system. Under predetermined operating conditions of the battery system 1, the BMS 14 may open the switchable valve of the exhaust assembly 15 to release a gas mixture from the interior of the housing 11.

[0089] BMS 14 is configured to detect abnormal conditions that could cause thermal runaway of battery pack 10, and is also configured to activate inert gas generation unit 13 when an abnormal condition is detected by BMS 14. The following will refer to... Figure 3The flowchart steps S1 and S2 describe the process in detail.

[0090] Figure 2 A battery system 1 according to a second embodiment of the present disclosure is shown. Basically, the second embodiment is similar to... Figure 1 The first embodiment shown, except that the inert gas generating unit 13.2 includes a first inert gas generator 13a and a second inert gas generator 13b, which will be described in more detail below. As for Figure 2 For the remaining features of the battery system, please refer to the description of the first embodiment above.

[0091] The first inert gas generator 13a of the inert gas generating unit 13.2 in the second embodiment can be a pyrotechnic inert gas generator, which generates inert gas through a chemical reaction. For example, the first inert gas generator 13a can generate nitrogen gas as an inert gas from the exothermic decomposition of sodium azide. When the BMS 14 detects an abnormal condition that may cause thermal runaway of the battery pack 10, the first inert gas generator 13a is activated by the BMS 14 to generate inert gas.

[0092] The second inert gas generator 13b of the inert gas generating unit 13.2 in the second embodiment can also be a pyrotechnic inert gas generator, which generates inert gas through a chemical reaction. For example, the second inert gas generator 13b can generate nitrogen gas as an inert gas through the exothermic decomposition of sodium azide. When the BMS 14 detects thermal runaway of the battery pack 10, the second inert gas generator 13b is activated by the BMS 14 to generate inert gas. Therefore, the BMS 14 is also configured to detect thermal runaway of the battery pack 10 and to activate the second inert gas generator 13b when an abnormal condition is detected by the BMS 14. In order to most effectively combat thermal runaway, the generation of inert gas should continue for a few seconds, for example, up to 20 seconds.

[0093] Figure 3 This is a flowchart illustrating an exemplary process for avoiding gas combustion in a battery system, such as... Figure 1 and Figure 2 The first and second embodiments are shown. The battery system of the first embodiment includes only an inert gas generating unit 13 with a single pyrotechnic gas generator, so only steps S1 and S2 described below can be performed, while the second embodiment includes an inert gas generating unit 13.2 with a first pyrotechnic gas generator 13a and a second pyrotechnic gas generator 13b. Therefore, in the following, reference will be made only to Figure 2 The exemplary process is explained using the second embodiment shown.

[0094] In step S1, BMS 14 detects an abnormal condition and generates a first activation signal, which is sent to the inert gas generating unit 13.2. More specifically, according to... Figure 2 In an exemplary implementation, temperature sensor 16 measures the temperature of the gas mixture present in housing 11. The measured temperature (hereinafter also referred to as housing temperature) is an input signal to BMS 14. The housing temperature is continuously monitored according to an exemplary subroutine implemented in the controller of BMS 14. If the housing temperature exceeds a given temperature limit, such as 90°C, the probability of thermal runaway increases significantly. Therefore, the subroutine generates a first activation signal for the inert gas generation unit 13.2.

[0095] It is important to note that monitoring the casing temperature is only one illustrative option for identifying anomalous conditions that could lead to thermal runaway. As described above in the "General Concepts" section, several other sensed or calculated key parameters of the battery system can be used to identify anomalous conditions. The selection of parameters depends on the battery system design and its operating conditions and should be appropriate for each specific application.

[0096] In step S2, the inert gas generating unit 13.2 receives a first activation signal from the BMS 14 and subsequently activates the first inert gas generator 13a. When the first inert gas generator 13a in the second embodiment is a pyrotechnic gas generator, the generation of inert gas will begin within milliseconds and completely flush the housing 11. Combustible gases discharged from the battery cell shortly before thermal runaway can be replaced and diluted by the generated inert gas, thereby preventing the ignition of the gas mixture. Preferably, the BMS 14 simultaneously sends an activation signal to the exhaust assembly 15 to temporarily open the switchable valve and ensure the safe release of the gas mixture from the interior of the housing 11.

[0097] Simultaneously with or after step S2, the battery system 1 may provide a maintenance reminder to the vehicle driver that the battery pack 10 must be inspected and repaired at a qualified service station.

[0098] In step S3, if the measures from step S2 are unsuccessful, the BMS 14 of the battery system 1 can detect thermal runaway. For example, temperature sensor 16 can measure a further increase in the casing temperature. A second subroutine executed in the controller of BMS 14 continues to monitor the casing temperature. If the casing temperature exceeds a given (second) temperature limit, such as 120°C, thermal runaway is considered to have been detected. Therefore, the second subroutine generates a second activation signal for the inert gas generation unit 13.2.

[0099] Again, it is important to note that monitoring the casing temperature is only one exemplary option for determining thermal runaway. As described above in the "General Concepts" section, several other sensed or calculated key parameters of the battery system can be used to determine thermal runaway. The selection of these parameters depends on the battery system design and its operating conditions and should be appropriate for each specific application.

[0100] In step S4, the inert gas generating unit 13.2 receives a second activation signal from the BMS 14 and subsequently activates the second inert gas generator 13b. When the second inert gas generator 13b in the second embodiment is a pyrotechnic gas generator, the generation of inert gas will begin within milliseconds and completely flush the housing 11. During thermal runaway, combustible gas is discharged from the damaged battery cells and burns within the housing 11. The generated inert gas will flush the housing 11, extinguish the fire, displace and dilute the combustible gas mixture, thereby preventing the gas mixture from reigniting. Preferably, the BMS 14 simultaneously sends an activation signal to the exhaust assembly 15 to temporarily open the switchable valve and ensure the safe release of the gas mixture from the interior of the housing 11. To prevent the battery pack 10 from drawing in air from the outside, which could reignite the gas mixture in the housing 11 (in the event of thermal runaway, the damaged battery cells may still discharge combustible gas), the second gas generator 13b preferably generates inert gas for a longer period than the first gas generator 13a, for example, 10 seconds.

[0101] Simultaneously with or after step S4, the battery system 1 may provide a maintenance reminder to the vehicle's driver that the battery pack 10 must be inspected and repaired at a qualified service station.

Claims

1. A battery system (1), comprising: The battery pack (10) includes a housing (11) and a plurality of battery cells housed within the housing (11); An inert gas generating unit (13.2) is configured to provide inert gas and flush the housing (11) with the inert gas. The battery management system (14) is configured to detect an abnormal condition that may cause thermal runaway of the battery pack (10) and activate the inert gas generating unit (13.2) when the abnormal condition is detected by the battery management system (14), and is also configured to detect thermal runaway and activate the inert gas generating unit (13.2) when the battery management system (14) has detected the thermal runaway; and A temperature sensor (16) is configured to measure the temperature inside the housing (11) and provide measurement data to the battery management system (14). The inert gas generating unit (13.2) includes: A first inert gas generator (13a) is configured to be activated when the abnormal condition is detected, generate the inert gas, and flush the housing (11) with the inert gas. A second inert gas generator (13b) is configured to be activated when the thermal runaway is detected, generate the inert gas and flush the housing (11) with the inert gas, the second inert gas generator generating the inert gas for a longer time than the first inert gas generator.

2. The battery system according to claim 1, wherein the first inert gas generator (13a) is a pyrotechnic inert gas generator.

3. The battery system according to claim 1, wherein the second inert gas generator (13b) is a pyrotechnic inert gas generator.

4. The battery system according to claim 1, wherein the temperature sensor (16) measures the temperature of the gas mixture present in the housing (11).

5. An electric vehicle comprising a battery system according to any one of the preceding claims.

6. A method for preventing gas combustion in a battery system (1), wherein the method comprises the following steps: a) Providing a battery system (1), the battery system (1) comprising: The battery pack (10) includes a housing (11) and a plurality of battery cells housed within the housing (11); An inert gas generating unit (13.2) is configured to generate inert gas and flush the housing (11) with the inert gas. The battery management system (14) is configured to detect an abnormal condition that may cause thermal runaway of the battery pack (10) and activate the inert gas generating unit (13.2) when the abnormal condition is detected by the battery management system (14), and is also configured to detect thermal runaway and activate the inert gas generating unit (13.2) when the battery management system (14) has detected the thermal runaway; and A temperature sensor (16) is configured to measure the temperature inside the housing (11) and provide measurement data to the battery management system (14); b) The abnormal condition is detected by the battery management system (14) and a first activation signal is generated. The first activation signal is sent to the inert gas generating unit (13.2) by the battery management system (14). c) After receiving the first activation signal from the battery management system (14), the inert gas is generated by the inert gas generating unit (13.2) and the inert gas is used to flush the housing (11). d) The thermal runaway is detected by the battery management system (14) and a second activation signal is generated, which is then sent to the inert gas generating unit (13.2) by the battery management system (14); and e) After receiving the second activation signal from the battery management system (14), the inert gas is generated by the inert gas generating unit (13.2) and the inert gas is used to flush the housing (11). The inert gas generating unit (13.2) includes a first inert gas generator (13a) and a second inert gas generator (13b). The first inert gas generator (13a) is configured to be activated and generate the inert gas when the abnormal condition is detected, and the second inert gas generator (13b) is configured to be activated and generate the inert gas when the thermal runaway is detected. In step c), the first inert gas generator (13a) generates the inert gas in response to the first activation signal of the battery management system (14) and uses the inert gas to flush the housing (11). In step e), the second inert gas generator (13b) generates the inert gas in response to the second activation signal of the battery management system (14) and flushes the housing (11) with the inert gas, and the second inert gas generator generates the inert gas for a longer time than the first inert gas generator.

7. The method of claim 6, wherein in step b), the abnormal condition that may lead to thermal runaway is determined by: (i) a battery management system subroutine for calculating the probability of thermal runaway and / or (ii) selected parameters controlling the battery system (1).

8. The method of claim 6, wherein in step d), the detection of thermal runaway is determined by: (i) a battery management system subroutine for calculating thermal runaway and / or (ii) selected parameters controlling the battery system (1).

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