Abstract:
An improved battery pack is disclosed. The battery pack includes: a plurality of battery cells; a protection circuit module for controlling charging and discharging of the plurality of battery cells; and a plurality of connection members for applying voltages output from the plurality of battery cells to the protection circuit module, at least one of the connection members having a damping resistive component.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2010-0033327, filed on Apr. 12, 2010, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    Aspects of one or more embodiments according to the present invention relate to a battery pack. 
         [0004]    2. Description of Related Art 
         [0005]    As portable electronic devices, for example, mobile phones, digital cameras, and laptop computers, are being widely used, development on batteries as a power source for driving the portable electronic devices is being actively conducted. 
         [0006]    A battery pack includes one or more battery cells and a protection circuit that controls charging and discharging of the battery cells, and batteries may be classified into lithium ion (Li-ion) batteries and nickel-cadmium (Ni—Cd) batteries, etc. The battery cell is a rechargeable battery (e.g., a secondary battery) and may be recharged for a number of times. 
       SUMMARY 
       [0007]    Aspects of one or more embodiments according to the present invention are directed toward a battery pack that may prevent fire from occurring due to a short between wires outputting voltages (e.g., intermediate voltages) from battery cells. 
         [0008]    Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments. 
         [0009]    According to one or more embodiments of the present invention, a battery pack includes: a plurality of battery cells; a protection circuit module for controlling charging and discharging of the plurality of battery cells; and a plurality of connection members for applying voltages output from the plurality of battery cells to the protection circuit module, at least one of the connection members having a damping resistive component. 
         [0010]    At least one of the connection members may include a first wire having the damping resistive component and a second wire formed of a material having a specific resistance value less than that of the first wire. 
         [0011]    The connection members may be coupled between the protection circuit module and the battery cells, the first wire may be coupled to and adjacent a terminal of the battery cells, and the second wire may be coupled to and adjacent an input terminal of the protection circuit module. 
         [0012]    At least one of the connection members may be a single electric wire having a damping resistance value. 
         [0013]    The connection members may be outside of the protection circuit module. 
         [0014]    The voltages output from the plurality of battery cells may have different magnitudes, and a number of connection members may correspond to a number of voltages output from the plurality of battery cells. 
         [0015]    According to one embodiment, a battery pack includes a plurality of battery cells; a protection circuit module; and a plurality of voltage sensing wires coupled between the battery cells and the protection circuit module, the voltage sensing wires being for supplying voltages of the battery cells to the protection circuit module. At least one of the voltage sensing wires is external to the protection circuit module and has a resistive component for preventing a short circuit between the protection circuit module and the battery cells. 
         [0016]    The at least one of the sensing wires may include a first portion and a second portion, the first portion and the second portion having different specific resistance values. One of the first portion or the second portion may include the resistive component. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    These and/or other aspects of the present invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
           [0018]      FIG. 1  is a perspective view of a battery pack according to an embodiment of the present invention; 
           [0019]      FIG. 2  is a circuit diagram schematically illustrating a protection circuit module included in the battery pack of  FIG. 1 ; 
           [0020]      FIG. 3  is a circuit diagram schematically illustrating connection members included in the battery pack of  FIG. 1 ; 
           [0021]      FIG. 4  is a perspective view of a battery pack according to another embodiment of the present invention; and 
           [0022]      FIG. 5  is a circuit diagram schematically illustrating connection members included in the battery pack of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Hereinafter, one or more embodiments of the present invention will be described in more detail with reference to the accompanying drawings. Here, when a first element is described as being coupled or connected to a second element, the first element may be directly coupled to the second element or indirectly coupled to the second element via one or more third elements. In the drawings, like reference numerals denote like elements. Accordingly, detailed description will not be repeated. 
         [0024]      FIG. 1  illustrates a battery pack  1  according to an embodiment of the present invention. 
         [0025]    Referring to  FIG. 1 , the battery pack  1  includes a battery  10 , a first combining member  20 , a second combining member  30 , a protection circuit module  40 , and connection members  50 . 
         [0026]    The battery  10  may include one or more battery cells (e.g., battery cells  11 ,  12 ,  13 , and  14 ) and may be charged or discharged through a charge terminal connected to an external device. The battery cells  11  through  14  each include an electrode assembly, a can, and a cap assembly, wherein the electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator. The can accommodates the electrode assembly and has an opening at a top end thereof, and the cap assembly is positioned on the opening of the can to seal the can. These battery cells  11  through  14  may be secondary batteries that may be rechargeable. In the embodiment of  FIG. 1 , the battery  10  includes the four battery cells  11  through  14 . However, the present invention is not limited thereto, and different number of battery cells may be included in the battery pack  1  according to a desired capacity of the battery pack  1 . 
         [0027]    The first combining member  20  and the second combining member  30  connects the battery cells  11  through  14  in series or in parallel and prevents or reduces movement of the battery cells  11  through  14 . The structures of the first combining member  20  and the second combining member  30  may vary according to the connection (e.g., in series or in parallel) of the battery cells  11  through  14 . In the embodiment of  FIG. 1 , the four battery cells  11  through  14  are connected to each other in series, and accordingly, the first combining member  20  may include conductive members that respectively electrically connect a positive electrode of the battery cell  11  with a negative electrode of the battery cell  12  and a positive electrode of the battery cell  13  with a negative electrode of the battery cell  14 . Also, the second combining member  30  may include a conductive member that electrically connects a positive electrode of the battery cell  12  with a negative electrode of the battery cell  13 . 
         [0028]    The protection circuit module  40  controls charging and discharging of the battery  10 . The protection circuit module  40  may include input terminals for receiving an output voltage of the battery  10  and at least one intermediate voltage (e.g., a voltage at a connection between two battery cells) output from the battery  10 . Also, the protection circuit module  40  may include a charging terminal that may connect to a charger or a load. 
         [0029]    The connection members  50  (e.g., voltage sensing wires), which are outside of the protection circuit module  40 , apply intermediate voltage outputs from the battery  10  to the protection circuit module  40 , and include a damping resistive component. According to the connection of the battery cells  11  through  14 , the battery  10  may output various intermediate voltages. The number of connection members  50  may correspond to the number of intermediate voltages to be output from the battery  10 , and the connection members  50  may apply each intermediate voltage to the corresponding input terminal of the protection circuit module  40 . In one embodiment of the present invention, the four battery cells  11  through  14  are connected to each other in series, and accordingly, three intermediate voltages having different magnitudes may be output. Accordingly, the battery pack  1  according to one embodiment may include three connection members  50 . 
         [0030]      FIG. 2  is a circuit diagram schematically illustrating the protection circuit module  40  included in the battery pack of  FIG. 1  according to an embodiment of the present invention. The protection circuit module  40  is described below in more detail with reference to  FIG. 2 . 
         [0031]    The protection circuit module  40  according to an embodiment may include a plurality of input and output terminals, first, second, and third switches SW 1 , SW 2 , and SW 3 , a plurality of fuses F 1  and F 2 , and first and second logic circuits  41  and  42 . 
         [0032]    A positive terminal (+) and a negative terminal (−) of the protection circuit module  40  are connected to an external device or a charger. 
         [0033]    The first switch SW 1  and the second switch SW 2  may include field effect transistors (FETs) and parasitic diodes D. In  FIG. 2 , the first switch SW 1  includes a transistor FET 1  and a parasitic diode D 1 , and the second switch SW 2  includes a transistor FET 2  and a parasitic diode D 2 . A connecting direction between source and drain of the FET 1  of the first switch SW 1  is opposite to that of the FET 2  of the second switch SW 2 . Accordingly, the FET 1  of the first switch SW 1  is connected to restrict a current flowing to the positive terminal from the battery  10  and to the battery  10  from the negative terminal, whereas the FET 2  of the second switch SW 2  is connected to restrict a current flowing to the battery  10  from the positive terminal and to the negative terminal from the battery  10 . Here, the FET 1  and the FET 2  are switching devices. However, the present invention is not limited thereto, and the FET 1  and the FET 2  may be electronic devices that perform other kinds of switching functions. Also, the parasitic diodes D 1  and D 2  respectively included in the first switch SW 1  and the second switch SW 2  allow a current to flow in a direction opposite to the direction by which a current flow is restricted. 
         [0034]    When the battery  10  is unstable, such as when an excessive current flows, the plurality of fuses F 1  and F 2  causes circuits to become open circuits to block the current flow. 
         [0035]    When an abnormal state occurs in the battery pack  1 , such as when an excessive current flows in a high current path, the third switch SW 3  is switched on to cut (e.g., melt) the fuses F 1  and F 2 . 
         [0036]    The first logic circuit  41  and the second logic circuit  42  may sense over-charging, over-discharging, and a temperature of the battery  10  or an excessive current flowing in the battery  10 . In order to control charging and discharging of the battery  10 , the first logic circuit  41  may control on/off states of the first switch SW 1  and the second switch SW 2 . In order to block a high current path and stop operation of the battery pack  1 , the second logic circuit  42  may control on/off states of the third switch SW 3 . 
         [0037]    The voltages output from the battery  10  are applied to the plurality of input terminals  1  through  5  of the protection circuit  40 . In  FIG. 2 , output voltages of the battery  10  are respectively applied to input terminals  1  and  5 , and a plurality of intermediate voltages output from the battery  10  are respectively applied to input terminals  2  through  4 . 
         [0038]    Also, the protection circuit module  40  according to the embodiment of  FIG. 2  may include a plurality of resistors R 1  through R 13 , a plurality of capacitors C 1  through C 13 , and a diode D 4 . 
         [0039]    The first logic circuit  41  and the second logic circuit  42  may receive the plurality of intermediate voltages from the battery  10  for cell balancing of the battery cells  11  through  14  (shown in  FIG. 1 ). Here, the protection circuit module  40  according to one embodiment does not include a device having a resistive component between the input terminals  2  through  4 , to which the intermediate voltages of the battery  10  are applied, and input terminals of the first logic circuit  41  and the second logic circuit  42 , to which the intermediate voltages are input. 
         [0040]      FIG. 3  is a circuit diagram schematically illustrating the connection members  50  included in the battery pack  1  of  FIG. 1 . 
         [0041]    Referring to  FIG. 3 , the output voltages of the battery  10  are respectively applied to the input terminals  1  and  5  of the protection circuit module  40 . Also, the intermediate voltages are generated from portions (e.g., connection points) by which the battery cells  11  through  14  are connected to each other and are respectively applied to the input terminals  2  through  4  of the protection circuit module  40 . Here, the intermediate voltages are transmitted to the protection circuit module  40  from the battery cells  11  through  14  by the connection members  50 . The connection members  50  each have a damping resistive component for preventing a fire when a short is generated. The connection members  50  may be formed of a material having a relatively high resistance value in order to behave as a damping resistive component. That is, the connection members  50  may each be a single electric wire formed of a material having a relatively high specific resistance value. 
         [0042]    In general, when an intermediate voltage of a battery is applied to a logic circuit included in a protection circuit module, a damping resistive component is formed between an input terminal of the protection circuit module to which the intermediate voltage is applied and an input terminal of the logic circuit to which the intermediate voltage is input, to protect the circuit. The damping resistive component is formed to cope with a problem such as a short that may be easily generated in the protection circuit. 
         [0043]    However, in the battery pack  1  according to the embodiment of  FIG. 2 , the damping resistive component in the protection circuit module  40  is removed, thereby simplifying an internal circuit of the protection circuit module  40 . Also, the damping resistive component for protecting a circuit of the protection circuit module  40  is formed in the connection members  50 . Accordingly, when a short occurs between the connection members  50 , since the connection members  50  have resistive components, and thus a fire generation due to a short may be reduced or prevented. 
         [0044]      FIG. 4  illustrates a battery pack  2  according to another embodiment of the present invention. The battery pack  2  has a structure and function similar to those of the battery pack  1  of  FIG. 1 , and thus only differences therebetween are described. 
         [0045]    Referring to  FIG. 4 , in the battery pack  2 , an intermediate voltage output from the battery  10  is applied to the protection circuit module  40  by using first connection members  60  and second connection members  61 . 
         [0046]    The first connection members  60  may each be a device or a wire having a damping resistive component. Each of the first connection members  60  is connected to a corresponding terminal of the battery cells  11  through  14 , for example, positive terminals (+) or negative terminals (−) thereof, and a corresponding one of the input terminals of the protection circuit module  40 . 
         [0047]    The second connection members  61  are each a wire having a specific resistance value less than that of each of the first connection members  60 , e.g., a wire formed of a material having a relatively small internal resistance. The second connection members  61  are each connected to the protection circuit module  40  between the battery cells  11  through  14  and the input terminals of the protection circuit module  40 . 
         [0048]      FIG. 5  is a circuit diagram schematically illustrating the connection members  60  and  61  included in the battery pack  2  of  FIG. 4 . 
         [0049]    As illustrated in  FIG. 4 , the first connection members  60  are each connected between the battery cells  11  through  14 , and each of the first connection members  60  is connected to a corresponding one of the second connection members  61 . Also, each of the second connection members  61  is connected to a corresponding one of the input terminals  2  through  4  of the protection circuit module  40  and applies an intermediate voltage to one of the input terminals  2  through  4 . 
         [0050]    As described above, in the battery pack  2  according to one embodiment, the damping resistive component in the protection circuit module  40  is removed, thereby simplifying an internal circuit of the protection circuit module  40 . Also, the first connection members  60  are each formed to have the damping resistive component and are connected to be adjacent to the input terminals of the protection circuit  40 , thereby reducing the likelihood of a fire occurring due to a short. 
         [0051]    It should be understood that the exemplary embodiments of the present invention described therein should be considered in a descriptive sense only and not for purposes of limitation, but, on the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, and equivalents thereof. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments.