Abstract:
A battery charging device includes: a charging unit coupled to a battery module, the battery module including at least one battery cell, wherein the charging unit is configured to charge the battery module; and a charge controller configured to: receive, from a battery management system managing to battery module, measurement information indicating whether or not an open circuit voltage (OCV) value of the battery module is within a predetermined voltage section; and transmit a discharge start signal to the battery management system to discharge the battery module in response to a value of the measurement information exceeding a predetermined number.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2014-0001441, filed in the Korean Intellectual Property Office on Jan. 6, 2014, the entire contents of which are incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    Aspects of embodiments of the present invention relate to a battery charging device and a battery charging method. 
         [0004]    2. Description of the Related Art 
         [0005]    Due to concerns about environmental disruption and resource exhaustion, interest in a system that can store power and that can efficiently use the stored power has increased. 
         [0006]    A power storage system may store newly generated power in a battery or may store power of a commercial system in a battery by coupling the battery to the commercial system. The power storage system in turn supplies power that is stored in the battery to the commercial system or a load. 
         [0007]    Rechargeable batteries capable of charging and discharging may also be used as part of a power storage system in order to store power. Rechargeable batteries differ from primary batteries in that rechargeable batteries can be repeatedly charged and discharged, while primary batteries typically are not designed to be recharged. Rechargeable batteries may be implemented as a single battery or as part of a battery module in which a plurality of batteries are combined as a single unit, depending on external devices to which it is applied. 
         [0008]    There is a need, however, to more efficiently and effectively perform the charge and discharge operation, for example, by controlling the battery system. 
         [0009]    The above information disclosed in this Background section is only for enhancement of understanding of the background and therefore it may contain information that does not constitute the prior art that is already known in this country to a person of ordinary skill in the art. 
       SUMMARY 
       [0010]    Aspects of embodiments of the present invention relate to a battery charging device that effectively charges a battery, and a battery charging method. 
         [0011]    Aspects of embodiments of the present invention include a battery charging device in which a battery charge is prevented in a flat section when charging the battery, and a battery charging method. 
         [0012]    Technical characteristics of the present invention are not limited to the above-described technical characteristics, and other technical aspects that are not described may be clearly understood by those skilled in the art from the following description. 
         [0013]    According to some embodiments of the present invention, a battery charging device includes: a charging unit coupled to a battery module, the battery module including at least one battery cell, wherein the charging unit is configured to charge the battery module; and a charge controller configured to: receive, from a battery management system managing to battery module, measurement information indicating whether or not an open circuit voltage (OCV) value of the battery module is within a predetermined voltage section; and transmit a discharge start signal to the battery management system to discharge the battery module in response to a value of the measurement information exceeding a predetermined number. 
         [0014]    The charge controller may be configured to receive open circuit voltage information of the battery module from the battery management system, and to transmit the discharge start signal to the battery management system in response to the open circuit voltage being within the predetermined voltage section. 
         [0015]    The charge controller may be configured to transmit a charging start signal to the battery management system to charge the battery module in response to the open circuit voltage being outside the predetermined voltage section. 
         [0016]    The charging unit may include a charging terminal coupled to the battery module and a coulomb counter configured to measure an open circuit voltage of the battery module using the charging terminal; and the charge controller may be configured to transmit the discharge start signal to the battery management system in response to the open circuit voltage value measured by the coulomb counter being within the predetermined voltage section. 
         [0017]    The charge controller may be configured to transmit a charging start signal to the battery management system to charge the battery module in response to the value of the measurement information being less than the predetermined number. 
         [0018]    The measurement information may include a count of the open circuit voltage being within the predetermined voltage section. 
         [0019]    According to some embodiments of the present invention, a battery charging device includes: a charging unit coupled to a battery module, the battery module including a battery cell, wherein the charging unit is configured to charge the battery module; and a charge controller configured to measure an open circuit voltage value of the battery module and to control the charging unit to discharge the battery module when the open circuit voltage value is within a predetermined voltage section. 
         [0020]    The charge controller may be configured to control the charging unit to charge the battery module in response to the open circuit voltage value being outside the predetermined voltage section. 
         [0021]    According to some embodiments of the present invention, a battery charging method includes: receiving, from a battery management system managing a battery module, measurement information indicating whether or not an open circuit voltage value of the battery module is within a predetermined voltage section, wherein the battery module includes a battery cell; and transmitting a signal for discharging the battery module to the battery management system in response to a value of the measurement information exceeding a predetermined number. 
         [0022]    The method may further include: receiving the open circuit voltage value from the battery management system; and generating the signal for discharging the battery module in response to the open circuit voltage value being within the predetermined voltage section. 
         [0023]    The method may further include transmitting a signal for charging the battery module to the battery management system in response to the open circuit voltage being outside the predetermined voltage section. 
         [0024]    The method may further include transmitting a signal for charging the battery module to the battery management system in response to the value of the measurement information being less than the predetermined number. 
         [0025]    The measurement information may include a count of the open circuit voltage being within the predetermined voltage section. 
         [0026]    According to some embodiments of the present invention, a battery charging method includes: measuring an open circuit voltage of a battery module including a battery cell; transmitting a signal for discharging the battery module to a battery management system managing the battery module in response to the open circuit voltage being within a predetermined voltage section; and transmitting a signal for charging the battery module to the battery management system in response to the open circuit voltage being outside the predetermined voltage section. 
         [0027]    Characteristics of the battery charging device and the battery charging method according to the present invention are as described below. 
         [0028]    According to at least one among example embodiments of the present invention, when charging the battery, the battery charge in the flat section may be prevented. 
         [0029]    The above characteristics of the present invention are not limited to the aforementioned aspects, and other characteristics not described above will be apparent to those skilled in the art from the disclosure of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]      FIG. 1  is a block diagram of a battery charging system according to embodiments of the present invention. 
           [0031]      FIG. 2  is a flowchart of a battery charging method according to some embodiments of the present invention. 
           [0032]      FIG. 3  is a graph of an OCV of a battery charged by a battery charging method according to embodiments of the present invention. 
           [0033]      FIG. 4  is a flowchart of a battery charging method according to embodiments of the present invention. 
           [0034]      FIG. 5  is a graph of an OCV of a battery charged by a battery charging method according to embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0035]    Aspects of embodiments of the present invention will be described more fully hereinafter with reference to the accompanying drawings, in which example embodiments are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. 
         [0036]    In addition, description of some features may be omitted for clarity, and like reference numerals designate like elements and similar constituent elements throughout the specification. 
         [0037]    Throughout this specification and the claims that follow, when it is described that an element is “coupled” to another element, the element may be “directly coupled” to the other element or “electrically coupled” to the other element through a third element. In addition, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. 
         [0038]    Now, a battery charging system and a battery charging method according to an example embodiment of the present invention will be described in some detail. 
         [0039]      FIG. 1  is a block diagram of a battery charging system according to an example embodiment of the present invention. As shown, a battery pack  10  may be coupled to a charging unit  20 . 
         [0040]    The battery pack  10  includes a battery module  12 , a battery management system (hereafter referred to as “BMS”)  14 , a memory  16 , a relay part  17 , and a discharge load  18 . 
         [0041]    Firstly, the battery module  12  may include a plurality of battery cells coupled in series or in parallel and that are capable of being charged and discharged. Here, each cell has a rechargeable battery which is capable of being (or configured to be) charged and discharged may be one selected from the group including (or consisting of) a nickel-cadmium battery, a lead storage battery, a nickel-hydrogen battery, a lithium-ion battery, and a lithium polymer battery, or any other suitable rechargeable battery. 
         [0042]    Also, the battery cell may be one selected from a group including (or consisting of) a cylindrical battery, a prismatic battery, a pouch battery, and equivalents thereof, however the shape of the battery cell is not limited thereto. The plurality of battery cells form one battery module  12 , and may be used, for example, as a power source of an electric vehicle or a hybrid vehicle. Further, the battery pack  10  includes a pack terminal a, and the pack terminal a may be coupled to a charge part  22  of an external charge unit  20  to charge the battery module  12 . 
         [0043]    Also, the BMS  14  is coupled to, mounted to, or arranged within the battery pack  10  to efficiency manage the charge and discharge operation of the battery module  12 . The BMS  14  manages the charge and discharge of the battery module  12 , and may measure open circuit voltage (hereafter referred to as “OCV”), current, temperature, etc., of each battery cell. Here, the OCV is a measurement of the voltage in a no-load state such that the discharge load  18  is not operated when measuring the OCV of the battery cell. 
         [0044]    The BMS  14  measures the OCV, the current, the temperature etc., of each battery cell, thereby estimating the OCV of the entire battery module, a state of charge (hereafter referred to as “SOC”) of each cell, and a state of health (hereafter referred to as “SOH”), and storing the OCV of the entire battery module, and the SOC and the SOH of each battery cell, which are estimated along with the OCV, the current, and the temperature of each battery cell to the memory  16  or transmitting them to the charging unit  20  connected by wire or wirelessly. 
         [0045]    In this case, the BMS  14  may include a coulomb counter measuring the charge, the temperature, the open circuit voltage, a load cycle, or time of each battery cell. 
         [0046]    Also, the BMS  14  may determine whether or not the OCV of the battery module  12  is changed within a flat section. For example, the BMS  14  may periodically measure the OCV of the battery module  12 . 
         [0047]    Also, the BMS  14  may accumulate a count of the number of times the OCV is measured within the flat section. The flat section may be a section or range of voltages in which a change amount of the OCV for the change of the SOC is no more than a threshold value (e.g., a predetermined threshold value) in a SOC-OCV relation curve. At this time, instead of the SOC, other factors such as a charging current, a discharge current, a charging elapsed time, a discharge elapsed time etc., may be used. 
         [0048]    That is, while the power of the battery module  12  is used, when the OCV that is periodically measured is within the flat section, the BMS  14  may count the number of times that the OCV is measured within the flat section and store it in the memory  16 . 
         [0049]    Also, according to the control of the BMS  14 , the relay part  17  may perform a switching operation of coupling the battery module  12  and the pack terminal a, or electrically coupling the battery module  12  and the discharge load  18 . 
         [0050]    Next, the discharge load  18  as a load consuming the power stored in the battery module  12  is coupled to the battery module  12  by the switching operation of the relay part  17 , thereby discharging the battery module  12 . 
         [0051]    The charging unit  20  includes the charge part (or charger)  22  and a charge control part (or charge controller)  24 . The charging unit  20  may charge the battery pack  10 . 
         [0052]    The charge part  22  charges the battery pack  10  and includes a charging terminal b. The charge part  22  charges the battery pack  10  if the charging terminal b is coupled to the pack terminal a of the battery pack  10 . At this time, a positive terminal of the charge part  22  may be coupled to a positive terminal of the battery pack  10 , and a negative terminal of the charge part  22  may be coupled to a negative terminal of the battery pack  10 . 
         [0053]    Thus, the charge part  22  supplies power supplied to an outer terminal c coupled to an external power source to the battery module  12  to charge the battery pack  10 . 
         [0054]    The charge control part  24  may charge or discharge the battery module  12  through the charging part  22  if the charging terminal b is coupled to the pack terminal a of the battery pack  10 . Also, the charge control part  24  may receive information regarding the voltage, the current, and the temperature of each battery pack  10 , the OCV, the SOH, and the SOC of the battery module  12 , or the OCV change of the battery module  12  from the BMS  14  of the battery cell. 
         [0055]    The BMS  14  and the charge control part  24  may include at least one of application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, and any other suitable units to perform other functions. 
         [0056]    Next, a method of charging the battery module  12  according to the number of times that the OCV of the battery module  12  is changed will be described with reference to  FIG. 2 . 
         [0057]      FIG. 2  is a flowchart of a battery charging method according to a first example embodiment of the present invention. The battery pack  10  is coupled to the load, thereby supplying the power stored to the battery pack  10  to the load. The load may be various electrical devices consuming the power such as home appliances or factory production equipment. 
         [0058]    Firstly, the BMS  14  measures the OCV of the battery module  12  (S 10 ). At this time, the BMS  14  periodically measures the OCV of the battery module  12 , as described in  FIG. 1 . 
         [0059]    Thus, the BMS  14  determines whether the power is consumed by the load such that the decreased OCV of the battery module  12  is within a flat section IN (S 12 ). Usage within the flat section IN will be described with reference to  FIG. 3 . 
         [0060]      FIG. 3  is a graph of an OCV of a battery charged by a battery charging method according to a first example embodiment of the present invention. As shown in the drawing, the BMS  14  may measure the OCV of the battery module  12  with an interval of time (e.g., a predetermined amount of time) tIN. 
         [0061]    The BMS  14  may initially measure the OCV of the battery module  12  at a time t 10 , and may measure the OCV of the battery module  12  at a time t 11  after the predetermined amount of time tIN from the time t 10 . Also, BMS  14  may measure the OCV of the battery module  12  at a time t 12  after the time t 11  by the predetermined amount of time tIN, a time t 13  after the time t 12  by the predetermined amount of time tIN, and a time t 14  after the time t 13  by the predetermined amount of time tIN. 
         [0062]    Firstly, at the time t 10 , the OCV of the battery module  12  may be measured as V1. 
         [0063]    At the time t 10 , if the battery pack  10  is coupled to the load and the power stored to the battery module  12  is used, the OCV of the battery pack  10  may be decreased. That is, by the use of the power, the OCV of the battery module  12  of the time t 11  is decreased to V2. 
         [0064]    Because the OCV is decreased from V1 to V2, the BMS  14  may determine whether the power usage from the time t 10  to the time t 11  is within the flat section IN (between V=H and V=L). 
         [0065]    Next, from the time t 11  to the time t 12 , because the OCV of the battery module  12  is decreased from V2 to V3, the BMS  14  may determine whether the power usage from the time t 11  to the time t 12  is within the flat section IN. 
         [0066]    From the time t 12  to the time t 13 , because the OCV of the battery module  12  is decreased from V3 to V4, the BMS  14  may determine whether the power usage from the time t 12  to the time t 13  is within the flat section IN. 
         [0067]    From the time t 13  to the time t 14 , because the OCV of the battery module  12  is decreased from V4 to V5, the BMS  14  may determine whether the power usage from the time t 13  to the time t 14  is within the flat section IN. 
         [0068]    Thus, because the OCV of the battery module  12  measured from the time t 10  to the time t 14  is within the flat section IN, the BMS  14  counts the usage number within the circuit flat section IN as a total of four times (S 14 ) and stores the usage number to the memory  16  (S 16 ). 
         [0069]    Next, the BMS  14  determines whether or not the battery pack  10  is coupled to the external charge unit  20  (S 18 ). For example, the coupling of the charge unit  20  may be determined through a sensor sensing whether the charging terminal b is coupled to the pack terminal a. Also, in a case that the battery pack  10  and the charge unit  20  are wirelessly coupled, the BMS  14  may determine the coupling of the charge unit  20  when receiving an initial connection start signal for a wireless power change. 
         [0070]    Further, the BMS  14  transmits the usage number stored to the memory  16  to the charge unit  20  (S 20 ). The BMS  14  and the charge unit  20  may be coupled through a separate terminal or a wireless communication network as well as the coupling between the pack terminal a and the charging terminal b. 
         [0071]    On the other hand, the BMS  14  may also transmit the OCV information V6 of the battery module  12  at the time t 15  to the charge control part  24 . However, when the measuring of the OCV of the battery module  12  is possible through the charging terminal b of the charging unit  20 , the transmission of the OCV information V6 of the battery module  12  may be omitted. 
         [0072]    Thus, the charge control part  24  determines whether the usage number exceeds a number (e.g., a predetermined number) (S 22 ). For example, the predetermined number may be set as 3 times. 
         [0073]    When the usage number exceeds the predetermined number, the charge control part  24  transmits a signal for starting the discharge of the battery module  12  (S 24 ). The charge control part  24  may transmit the signal for starting the discharge of the battery module  12  to the BMS  14  to discharge the battery module  12 . Also, the charge control part  24  appropriately controls the charging part  22  to discharge the battery module  12 . 
         [0074]    At this time, the charge control part  24  may discharge the battery module  12  by further considering the OCV of the battery module  12 . 
         [0075]    For example, in a case that the charge control part  24  receives information for the current OCV of the battery module  12  from the BMS  14  or measures the current OCV of the battery module  12  through the charging terminal b, if the OCV of the battery module  12  is less than a lowest limitation value L of the flat section, the usage number is not determined, and a signal for starting the charge of the battery module  12  may be transmitted to BMS  14  S 32 . 
         [0076]    Further, if the OCV of the battery module  12  exceeds the lowest limitation value L of the flat section, the charge control part  24  determines whether the usage number exceeds the predetermined number, and if the usage number exceeds the predetermined number, the charge control part  24  transmits the discharge start signal to the BMS  14 , thereby discharging the battery module  12 . 
         [0077]    When the charge control part  24  transmits the signal starting the discharge of the battery module  12  to the BMS  14 , the BMS  14  controls the switching operation of the relay part  17  to discharge the battery module  12  (S 26 ) so as to couple the battery module  12  to the discharge load  18 . 
         [0078]    At the time t 15  of  FIG. 3 , if the charging unit  20  and the battery pack  10  are coupled, the step S 20  to the step S 23  are performed, and the charge control part  24  may transmit the signal for discharging the power stored to the battery module  12  to the BMS  14 . 
         [0079]    Also, when the usage number is less than the predetermined number, the charge control part  24  may transmit the signal for starting the charge of the battery module  12  to the BMS  14  (S 32 ). 
         [0080]    After the discharge is started, the BMS  14  transmits the information for the OCV of the battery module  12  to the charge control part  24  (S 28 ). If the measuring of the OCV of the battery module  12  is possible by the charging terminal b of the charging unit  20 , the step S 28  may be omitted. 
         [0081]    Thus, the charge control part  24  determines whether the OCV of the battery module  12  leaves the flat section IN (S 30 ). For example, because the power stored to the battery module  12  is discharged, the charge control part  24  may determine whether or not the OCV of the battery module  12  is less than a threshold value CP. 
         [0082]    When it is determined that the OCV of the battery module  12  is less than the threshold value CP of the flat section IN, the charge control part  24  starts the charge of the battery module  12  (S 30 ). At the time t 16  of  FIG. 3 , the charge control part  24  may transmit the signal for starting the charge of the battery module  12  to the BMS  14  and supply the power to the battery module  12  through the charging part  22 . 
         [0083]    Thus, the BMS  14  controls the switching operation of the relay part  17  to charge the battery module  12  so as to couple the battery module  12  to the pack terminal a (S 34 ). 
         [0084]    Next, the charge unit  20  measuring the OCV of the battery module  12  and charging the battery module  12  will be described with reference to  FIG. 4 . 
         [0085]      FIG. 4  is a flowchart of a battery charging method according to an example embodiment of the present invention. As shown in the drawing, the charge unit  20  is coupled to the battery pack  10  (S 40 ). 
         [0086]    The charge control part  24  of the charge unit  20  measures the OCV of the battery module  12  (S 42 ). For example, the charge control part  24  may measure the OCV of the battery module  12  by the charging terminal b. At this time, the charge control part may include the coulomb counter measuring the charge, the temperature, the open circuit voltage, and the load cycle or time of the battery module  12 . 
         [0087]    Thus, the charge control part  24  may determine whether or not the OCV of the battery module  12  is within the flat section IN. The OCV of the battery module  12  of the flat section IN with reference to  FIG. 4  will now be described. 
         [0088]      FIG. 5  is a graph of an OCV of a battery charged by a battery charging method according to a second example embodiment of the present invention. As shown in the drawing, the OCV of the battery module  12  at the time t 21  is V7. The voltage value V7 may be determined as a value within the flat section IN (between V=H and V=L). 
         [0089]    For example, the charge control part  24  may determine whether the OCV of the battery module  12  is within the flat section IN by using a plurality of comparators. The charge control part  24  may set the reference voltage of a first input terminal of a comparator as the highest limitation value H and the lowest limitation value L, and may apply the OCV of the battery module  12  to a second input terminal of the comparator. Thus, the charge control part  24  may determine whether or not the OCV of the battery module  12  is within the flat section IN by using the output of the comparator. 
         [0090]    Next, when the OCV of the battery module  12  is within the flat section IN, the charge control part  24  transmits the signal for starting the discharge of the battery module  12  (S 46 ). 
         [0091]    Next, when it is determined that the OCV of the battery module  12  leaves the flat section IN according to the discharge, the charge control part  24  transmits the signal for starting the charge of the battery module  12  (S 48 ). 
         [0092]    For example, the charge control part  24  measures the OCV of the battery module  12  at the time t 22 , when the measured OCV is less than the threshold value CP, the signal charging the battery module  12  may be transmitted to the battery management system. 
         [0093]    While aspects of the present invention have been described in connection with example embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims and their equivalents. Therefore, those skilled in the art will understand that various modifications and other equivalent exemplary embodiments may be possible. In addition, a person of ordinary skill in the art may omit some of the components described in the present specification without deteriorating the performance, or may add components in order to improve the performance. Further, a person of ordinary skill in the art may change the sequence of the processes described in the present specification according to the process environments or equipment. Therefore, the scope of the present invention should be defined by the appended claims and their equivalents, not by the described example embodiments. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Description of Symbols 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 10: battery pack 
                 12: battery module 
               
               
                   
                 14: BMS 
                 16: memory 
               
               
                   
                 17: relay part 
                 18: discharge load 
               
               
                   
                 20: charge unit 
                 22: charge part 
               
               
                   
                 24: charge control part