Patent Publication Number: US-2022223988-A1

Title: Battery Pack

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Korean Patent Application No. 10-2021-0003987 filed Jan. 12, 2021, the disclosure of which is hereby incorporated by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present disclosure relates to a battery pack. 
     2. Description of Related Art 
     A secondary battery is a battery that can be repeatedly used because it can be charged and discharged. The secondary battery may consist of a single battery cell and may be used in small portable electronic devices such as mobile phones, notebook computers, computers, cameras, camcorders, or may consist of a battery pack including a plurality of battery cells and may be used as a power source for driving motors such as high-output hybrid electric vehicles (HEV), electric vehicles (EV), and the like. 
     A battery used in a hybrid electric vehicle (HEV) or an electric vehicle (EV) must realize high output and high capacity. For this reason, a plurality of batteries constitute a battery pack as a single unit, and a plurality of such battery packs may be electrically connected in series or parallel to be used as a high-capacity and high-output power source. 
     As described above, as the battery pack is used as a high-capacity high-output power source, the battery pack is being improved to have higher energy density. However, as the battery pack has higher energy density, when some battery modules of the battery pack are damaged, a temperature of the undamaged battery modules also rapidly rises and thermal propagation may occur. Such thermal propagation of the battery pack poses a great risk to user safety. 
     SUMMARY OF THE INVENTION 
     An aspect of the present disclosure is to provide a battery pack in which thermal propagation is prevented. 
     According to an aspect of the present disclosure, a battery pack includes: a battery module array including a plurality of battery modules coupled in series and having first and second terminals, each of the plurality of battery modules including at least one battery cell, a current blocking element coupled to the battery cell and opened when an overcurrent is applied, and a sensor unit measuring state information of the battery cell and transmitting the measured information; a battery blocking unit including a first switch unit coupled to the first terminal in series, a second switch unit coupled to the second terminal in series, and a third switch unit coupled to the first and second terminals; and a battery management system turning on the third switch unit to open the current blocking element when the measured information exceeds a predetermined threshold value. 
    
    
     
       BRIEF DESCRIPTION OR DRAWINGS 
       The above and other aspects, features and other advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a schematic block diagram of a battery pack according to an embodiment of the present disclosure; 
         FIG. 2  is a block diagram illustrating control of a battery management system; and 
         FIGS. 3 to 5  are diagrams illustrating an explosion prevention function of the battery pack of  FIG. 1 . 
     
    
    
     DESCRIPTION OF THE INVENTION 
     The following detailed description is provided to assist the reader in gaining a comprehensive understanding of the methods, apparatuses, and/or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatuses, and/or systems described herein will be apparent to one of ordinary skill in the art. The sequences of operations described herein are merely examples, and are not limited to those set forth herein, but may be changed as will be apparent to one of ordinary skill in the art, with the exception of operations necessarily occurring in a certain order. Also, descriptions of functions and constructions that would be well known to one of ordinary skill in the art may be omitted for increased clarity and conciseness. 
     The features described herein may be embodied in different forms, and are not to be construed as being limited to the examples described herein. Rather, the examples described herein have been provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to one of ordinary skill in the art. 
     Herein, it is noted that use of the term “may” with respect to an embodiment or example, e.g., as to what an embodiment or example may include or implement, means that at least one embodiment or example exists in which such a feature is included or implemented while all examples and examples are not limited thereto. 
     Throughout the specification, when an element, such as a layer, region, or substrate, is described as being “on,” “connected to,” or “coupled to” another element, it may be directly “on,” “connected to,” or “coupled to” the other element, or there may be one or more other elements intervening therebetween. In contrast, when an element is described as being “directly on,” “directly connected to,” or “directly coupled to” another element, there can be no other elements intervening therebetween. 
     As used herein, the term “and/or” includes any one and any combination of any two or more of the associated listed items. 
     Although terms such as “first,” “second,” and “third” may be used herein to describe various members, components, regions, layers, or sections, these members, components, regions, layers, or sections are not to be limited by these terms. Rather, these terms are only used to distinguish one member, component, region, layer, or section from another member, component, region, layer, or section. Thus, a first member, component, region, layer, or section referred to in examples described herein may also be referred to as a second member, component, region, layer, or section without departing from the teachings of the examples. 
     Spatially relative terms such as “above,” “upper,” “below,” and “lower” may be used herein for ease of description to describe one element&#39;s relationship to another element as illustrated in the figures. Such spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, an element described as being “above” or “upper” relative to another element will then be “below” or “lower” relative to the other element. Thus, the term “above” encompasses both the above and below orientations depending on the spatial orientation of the device. The device may also be oriented in other manners (for example, rotated 90 degrees or at other orientations), and the spatially relative terms used herein are to be interpreted accordingly. 
     The terminology used herein is for describing various examples only, and is not to be used to limit the disclosure. The articles “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “includes,” and “has” specify the presence of stated features, numbers, operations, members, elements, and/or combinations thereof, but do not preclude the presence or addition of one or more other features, numbers, operations, members, elements, and/or combinations thereof. 
     Due to manufacturing techniques and/or tolerances, variations of the shapes illustrated in the drawings may occur. Thus, the examples described herein are not limited to the specific shapes illustrated in the drawings, but include changes in shape that occur during manufacturing. 
     The features of the examples described herein may be combined in various manners as will be apparent after gaining an understanding of the disclosure of this application. Further, although the examples described herein have a variety of configurations, other configurations are possible as will be apparent after gaining an understanding of the disclosure of this application. 
     The drawings may not be to scale, and the relative sizes, proportions, and depiction of elements in the drawings may be exaggerated for the purposes of clarity, illustration, and convenience. 
     Hereinafter, exemplary embodiments of the present disclosure will be described with reference to various examples. However, embodiments of the present disclosure may be modified to have various other forms, and the scope of the present disclosure is not limited to the embodiments described below. 
     Referring to  FIGS. 1 and 2 , a battery pack according to an embodiment will be described.  FIG. 1  is a schematic block diagram of a battery pack according to an embodiment of the present disclosure, and  FIG. 2  is a block diagram illustrating control of a battery management system. 
     Referring to  FIG. 1 , a battery pack  10  according to an embodiment of the present disclosure may include a battery module array  100  having first and second terminals N 1  and N 2 , a battery blocking unit  200  connected to the first and second terminals N 1  and N 2  of the battery module array  100 , and a battery management system (BMS)  300 . The battery pack  10  may include first and second output terminals CP and CN for supplying a current to an external device  20 . 
     The battery module array  100  may include a plurality of battery modules  110  connected in series. Each of the plurality of battery modules  110  may include one or more battery cells  111 , and may include a current blocking element  112  connected to the battery cell  111  in series, and a sensor unit  113 . When a plurality of battery cells  111  are employed in the battery module  110 , the plurality of battery cells  111  may be connected to each other in series, parallel, and series-parallel. The battery module array  100  according to an embodiment may have a structure in which first to sixth battery modules  110 - 1  to  110 - 6  are connected in series. According to an embodiment, a manual service disconnector module  120  may be connected to the battery module  110  in series. 
     As the battery cell  111 , various types of secondary batteries that can be repeatedly charged and discharged may be employed. In one embodiment, the battery cell  111  may be a lithium ion battery. 
     The current blocking element  112  is an element opened when an overcurrent flows through the battery module  110  to protect the battery module  110 , and in an embodiment, the current blocking element  112  may be a fuse, but is not limited thereto. The current blocking element  112  may be opened when an overcurrent flows through the battery module  110  to electrically separate the plurality of battery modules  110  connected in series, respectively. 
     The sensor unit  113  may measure state information of the battery module  110  and transmit a measured information to the battery management system  300 . The sensor unit  113  may include various sensors for measuring state information of the battery module  110 . The sensor unit  113  may include at least one of a temperature sensor  113 - 1  and a gas sensor  113 - 2 , and may include a voltmeter according to an embodiment. In addition, the sensor unit  113  may include a plurality of sensors. For example, the sensor unit  113  may include a temperature sensor  113 - 1  and a gas sensor  113 - 2 , the temperature sensor  113 - 1  may measure a temperature of the battery module  110 , and transmit a measured information thereof to the battery measurement system  300 , and the gas sensor  113 - 2  may measure gas concentration in the battery module  110  and transmit a measured information thereof to the battery management system  300 . 
     Referring to  FIGS. 1 and 2 , the battery management system  300  may receive a measured information transmitted from the sensor unit  113  disposed in each of the battery modules  110 , compare the measured information with a predetermined threshold value, to determine whether the battery module  110  normally operates. The battery management system  300  may determine that the measured information detected by the sensor unit  113  is lower than or equal to the predetermined threshold value as a “normal state” in which the battery module  110  normally operates, and determine that the measured information detected by the sensor unit  113  exceeds the predetermined threshold value as an “abnormal state” in which the battery module  110  does not operate normally. Such an abnormal state of the battery module  110  may occur when the battery cell  111  is damaged by an external factor such as an impact. In the battery module  110  exceeding a threshold value, ignition may start, heat generated in the ignited battery module  110  is transferred to a neighboring battery module  110 , and an entire battery module array  100  is ignited and combustible gas is ejected. In this case, when the battery module array  100  is in a high-voltage energy state, a so-called ‘massive explosion’ in which the entire battery module array  100  explodes beyond simple ignition may occur. Such a large-scale explosion is more severe when the battery module array  100  is in a high voltage state. In this way, the battery pack  10  in an embodiment electrically separates the plurality of battery modules  110  of the battery module array  100  from each other before the battery module array  100  explodes on a large scale, and changes to a low voltage state, such that the large-scale explosion may be reduced to a small-scale explosion, or it may be stopped with simple ignition. This will be described later in detail. 
     The predetermined threshold value at which the battery management system  300  determines an abnormal state is a pre-stored value, and various values capable of comparing the measured information transmitted from the sensor unit  113  may be pre-stored. For example, when a temperature is measured by the sensor unit  113 , the predetermined threshold value may be a temperature value. In addition, when gas concentration is measured by the sensor unit  113 , the predetermined threshold value may be a gas concentration value. Also, when the voltage is measured, the predetermined threshold value may be a voltage value. Specifically, for example, when the temperature is measured by the sensor unit  113 , and the battery cells included in the battery module  110  are lithium-ion battery cells, the predetermined threshold value may be 50° C. In addition, when a voltage is measured by the sensor unit  113 , the predetermined threshold value may be based on a value at which a discharge rate of 50 Crate or more lasts for several seconds. 
     In addition, even when the measured information transmitted from the sensor unit  113  of any one of the battery modules  110  among the plurality of battery modules  110  is higher than the measured information transmitted from the sensor unit  113  of the other battery modules  110  by exceeding 3° C., the battery management system  300  may determine that the corresponding battery module  110  as an abnormal state. 
     In addition, when the sensor unit  113  includes both a temperature sensor  113 - 1  and a gas sensor  113 - 2 , the battery management system  300  may be determined as an abnormal state only when both the measured information measured by the temperature sensor  113 - 1  and the measured information measured by the gas sensor  113 - 2  exceed predetermined threshold values. 
     When the battery module  110  is determined to be in a normal state, the battery management system  300  may turn on first and second switch units  210  and  220 , such that a current of the battery module array  100  may be supplied to an external device  20 . In addition, when the battery module  110  is determined to be in an abnormal state, a third switch unit  230  may be turned on to short-circuit the battery module array  100 , and by allowing an overcurrent to flow in the short-circuited battery module array  100 , the battery management system  300  may open the current blocking element  112  included in each battery module  110 , and thereby, each battery module  110  may be electrically separated and a problem of thermal propagation may be prevented in advance. 
     Referring to  FIG. 1 , a battery blocking unit  200  may be disposed between the battery module array  100  and an external device  20 , and may block a current transmitted from the battery pack  10  to the external device  20  under control of the battery management system  300 . That is, an input unit of the battery blocking unit  200  may be connected to first and second terminals N 1  and N 2  of the battery module array  100 , and an output unit thereof may be connected to first and second output terminals CP and CN of the battery pack  10 . 
     The battery blocking unit  200  may include a first switch unit  210  connected to the first terminal N 1  in series, a second switch unit  220  connected to the second terminal N 2  in series, and a third switch unit  230  connecting the first and second terminals N 1  and N 2  to each other. The first to third switch units  210  to  230  may be formed of various types of switch elements. At least one of the first to third switch units  210  to  230  may include a plurality of switch elements, and a resistance element may be further disposed in any one of the switch units. In an embodiment, the first switch unit  210  may further include a resistance element  213  in which the first and second switch elements  211  and  212  are connected in parallel to each other, and having the second switch element  212  connected in series. 
     In an embodiment, the first to third switch units  210  to  230  may be configured as power relays. The first to third switch units  210  to  230  may be turned on or off according to the control of the battery management system  300 , to block a current flowing through the first to third switch units  210  to  230 . When the battery module array  100  is in a normal state, the first and second switch units  210  and  220  may be turned on and the third switch unit  230  may be turned off, so that the current supplied from the battery module array  100  may be supplied to the external device  20 . In addition, when the battery module array  100  is in an abnormal state, the third switch unit  230  may be turned on to short-circuit the first and second terminals N 1  and N 2  of the battery module array  100  to each other. When the first and second terminals N 1  and N 2  are short-circuited by each other, an overcurrent may be generated in the battery module array  100 , and a current blocking element  112  included in each battery module  110  included in the battery module array  100  may be opened. Accordingly, each of the battery modules  110  included in the battery module array  100  may be electrically separated from each other. This has an effect of separating one high-capacity and high-output battery module array  100  into a plurality of low-capacity and low-output battery modules  110 . Accordingly, it is possible to prevent thermal propagation from occurring in the battery pack  10  in a high-capacity and high-output state. 
     This will be described in detail with reference to  FIGS. 3  to  5 . 
       FIG. 3  illustrates a case in which the battery module  110  of the battery pack  10  is in a normal state, and in  FIG. 3 , first and second switch units  210  and  220  of the battery blocking unit  200  may be turned on, respectively, and a third switch unit may be turned off, so that a current Il supplied from the battery module array  100  may be supplied to an external device  20 . 
       FIG. 4  illustrates a case in which any one of the battery modules  110  of the battery pack  10  is in an abnormal state. In an embodiment, it is assumed that a first battery module  110 - 1  is damaged and is in an abnormal state. Since the first battery module  110 - 1  in an abnormal state ignites and an internal temperature rises rapidly, a high temperature, higher than a predetermined threshold value, may be measured or high concentration of gas may be detected in the sensor unit  113 . Since the measured information transmitted from the sensor unit  113  exceeds a predetermined threshold value, an ON signal may be applied to the third switch unit  230  of the battery blocking unit  200  such that first and second terminals N 1  and N 2  of the battery module array  100  may be short-circuited. According to an embodiment, the third switch unit  230  may be turned on and the first and second switch units  210  and  220  may be turned off. When the first and second terminals N 1  and N 2  are short-circuited, a closed-loop is formed, and an overcurrent I 2  flows through the battery module array  100 . 
     Accordingly, as shown in  FIG. 5 , a current blocking element  112  included in each of the battery modules  110  is melted and opened by a high current, so that each battery module  110  is electrically separated from others thereof. As described above, before the battery module array  100  explodes on a large scale, when the plurality of battery modules  110  of the battery module array  100  are electrically separated from each other, the battery module array  100  is changed to a low-voltage state, and explosion may be reduced compared to a high-voltage state. 
     As set forth above, in a battery pack according to the technical idea of the present disclosure, when a problem occurs in some battery modules and there is a possibility to escalate into thermal propagation, by electrically separating the battery modules constituting the battery pack from each other, a problem occurring in some battery modules can affect neighboring battery modules and prevent the problem from escalating into thermal propagation. 
     The present disclosure may, however, be exemplified in many different forms and should not be construed as being limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. 
     While example embodiments have been shown and described above, it will be apparent to those skilled in the art that modifications and variations could be made without departing from the scope of the present inventive concept as defined by the appended claims.