Patent Publication Number: US-2015061595-A1

Title: Battery protection system and battery protection method using the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority under 35 U.S.C. §119 to U.S. Provisional Application No. 61/872,254, filed on Aug. 30, 2013, and entitled: “Battery Protection System and Battery Protection Method Using The Same,” which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     1. Field 
     Embodiments relate to a battery protection system and a battery protection method using the same. 
     2. Description of the Related Art 
     Recently, various portable devices have been developed and are widely used. Accordingly, batteries for supplying power to the portable devices have become increasingly important. 
     SUMMARY 
     Embodiments are directed to a battery protection system, including a first battery, a first line coupled to a first electrode of the first battery, and a second line coupled to a second electrode of the first battery, the first and second electrodes being of opposite polarity, a measurement unit measuring a voltage at first and second measurement terminals, the first measurement terminal being connected to the first electrode by the first line, the second measurement terminal being connected to the second electrode by the second line, and a protection unit controlling a voltage of the first battery according to a generated voltage, the generated voltage being determined by adjusting the measured voltage according to a first voltage drop across the first line, a second voltage drop across the second line, or both the first voltage drop and the second voltage drop. 
     The protection unit may stop a charging operation of the first battery when the generated voltage exceeds a reference voltage. 
     The protection unit may stop a discharging operation of the first battery when the generated voltage is lower than a reference voltage. 
     The first electrode may be a positive electrode and the second electrode may be a negative electrode, the measured voltage may be a potential across the first and second measurement terminals when the first battery is being charged, and the generated voltage may be determined by adjusting the measured voltage by subtracting the first voltage drop and the second voltage drop from the measured voltage. 
     The first electrode may be a positive electrode and the second electrode may be a negative electrode, the measured voltage may be a potential across the first and second measurement terminals when the first battery is being discharged, and the generated voltage may be determined by adjusting the measured voltage by adding the first voltage drop and the second voltage drop to the measured voltage. 
     The battery protection system may further include a second battery in series with the first battery, a first electrode of the second battery being connected to the second electrode of the first battery, a third measurement terminal connected to a second electrode of the second battery by a third line, and a control unit that selects from among the first, second, and third measurement terminals, the measured voltage being measured at the selected measurement terminals. 
     Embodiments are also directed to a battery protection system, including a first line coupled to a first electrode of a battery, and a second line coupled to a second electrode of the battery, the first and second electrodes being of opposite polarity, a measurement unit measuring a voltage at first and second measurement terminals, the first measurement terminal being connected to the first electrode by the first line, the second measurement terminal being connected to the second electrode by the second line, and a protection unit, the protection unit controlling a voltage of the battery according to a generated voltage, the generated voltage being determined by adjusting the measured voltage potential according to a first voltage drop across the first line, a second voltage drop across the second line, or both the first voltage drop and the second voltage drop. 
     Embodiments are also directed to a method of controlling a battery voltage, including determining a first voltage across measurement terminals that are connected to first and second electrodes of a first battery, respectively, determining a second voltage by adding or subtracting a predetermined value to the first voltage, and interrupting a charge or discharge operation of the first battery when the second voltage is at a reference voltage. 
     The predetermined value may be subtracted from the first voltage, and the charge operation may be interrupted when the second voltage is at the reference voltage. 
     The predetermined value may be added to the first voltage, and the discharge operation may be interrupted when the second voltage is at the reference voltage. 
     A second battery may be connected to the first battery, a first measurement terminal being connected to a first electrode of the first battery, a second measurement terminal being connected to a second electrode of the first battery and a first electrode of the second battery, and a third measurement terminal being connected to a second electrode of the second battery, and the first and second batteries being connected in series between the first measurement terminal and the third measurement terminal, and the method may further include selecting two among the first, second, and third measurement terminals, and determining the first voltage across the selected measurement terminals. 
     Embodiments are also directed to a battery protection system, including a battery formed to include at least one battery pack in which first and second battery cells are connected in parallel, a first line for connecting positive electrodes of the battery cells, a second line for connecting negative electrodes of the battery cells, a third line for connecting a positive electrode of the battery pack with a protection module, a fourth line for connecting a negative electrode of the battery pack with the protection module, and the protection module for performing a protection operation which cuts off charging or discharging of the battery. 
     The protection module may determine a battery pack voltage value by subtracting a voltage drop from a measured voltage of the battery pack, and may control the charging and discharging of the battery by using the determined value. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features will become apparent to those of skill in the art by describing in detail example embodiments with reference to the attached drawings in which: 
         FIG. 1  illustrates a structure of a battery protection system in accordance with an example embodiment. 
         FIG. 2  illustrates a flowchart showing a battery protection method in accordance with another example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey example implementations to those skilled in the art. 
     In the drawing figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. Like reference numerals refer to like elements throughout. 
     Throughout this specification, when a part is described as “comprising (or including)” constituent elements, this indicates that the part may further include other constituent elements unless particularly otherwise defined. In addition, the terms “-er”, “-or”, and “module” described in the specification refer to units for processing at least one function and operation, and can be implemented by hardware components or software components and combinations thereof. 
       FIG. 1  illustrates a structure of a battery protection system  1  in accordance with an example embodiment. 
     Referring to  FIG. 1 , the battery protection system  1  of the present example embodiment may include a battery  20 , a protection module  30 , and a switch unit  40 . The battery protection system  1  may measure a voltage of the battery  20  to perform a protection operation by using the measured voltage of the battery  20 . 
     The protection operation indicates an operation that cuts off an electrical connection with external circuits of the battery  20  (external circuits may be, e.g., a charger  50 , a load  60 , etc.) when the measured voltage of the battery  20  exceeds a reference voltage. 
     In the example embodiment shown in  FIG. 1 , the charger  50  and the load  60  are respectively connected to opposite ends of the battery  20 . The charger  50  serves to supply a charging voltage for charging the battery  20 . The load  60  is operated using power supplied from the battery  20 . One end of the charger  50  and one end of the load  60  are connected to a positive electrode of the battery  20 . The other ends of the charger  50  and the load  60  are connected to a negative electrode of the battery  20 . 
     The battery  20  may include a first battery pack  210  in which a plurality of battery cells  211  and  212  are connected (e.g., in parallel), a second battery pack  220  in which a plurality of battery cells  221  and  222  are connected (e.g., in parallel), and a third battery pack  230  in which a plurality of battery cells  231  and  232  are connected (e.g., in parallel). 
     Positive electrodes of the battery cells  211  and  212  are connected to a first line L 1 , and negative electrodes of the battery cells  211  and  212  are connected to a second line L 2 . 
     Positive electrodes of the battery cells  221  and  222  are connected to a fifth line L 5 , and negative electrodes of the battery cells  221  and  222  are connected to a sixth line L 6 . 
     Positive electrodes of the battery cells  231  and  232  are connected to an eighth line L 8 , and negative electrodes of the battery cells  231  and  232  are connected to a ninth line L 9 . 
     A third line L 3  is connected to the first line L 1 , and a fourth line L 4  is connected to the second line L 2  and the fifth line L 5 . A seventh line L 7  is connected to the sixth line L 6  and the eighth line L 8 , and a tenth line L 10  is connected to the ninth line L 9 . 
     The protection module  30  may include measurement terminals  311  to  314 , a selecting unit  320 , a control unit  330 , and a protection unit  340 . 
     The measurement terminal  311  of the protection module  30  is connected to the third line L 3 , and the measurement terminal  312  of the protection module  30  is connected to the fourth line L 4 . The measurement terminal  313  of the protection module  30  is connected to the seventh line L 7 , and the measurement terminal  314  of the protection module  30  is connected to the tenth line L 10 . 
     The selecting unit  320  may select a plurality of measurement terminals to correspond to selected battery packs or battery cells according to a selection control signal CONT 1  of the control unit  330 . The selecting unit  320  may receive voltages of the battery pack or battery cell selected through the selected measurement terminals. 
     For example, the selecting unit  320  may select the measurement terminal  311  and the measurement terminal  312  to correspond to the first battery pack  210  according to a selection control signal CONT 1  that selects the first battery pack  210 . 
     The selecting unit  320  may receive a positive electrode potential of the first battery pack  210  through the terminal  311 . The selecting unit  320  may transmit the positive electrode potential of the first battery pack  210  to the control unit  330  through a positive electrode line PL 1  and to the protection unit  340  through a positive electrode line PL 2 . 
     The selecting unit  320  may receive a negative electrode potential of the first battery pack  210  through the terminal  312 . The selecting unit  320  may transmit the negative electrode potential of the first battery pack  210  to the control unit  330  through a negative electrode line NL 1  and to the protection unit  340  through a negative electrode line NL 2 . 
     The protection unit  340  may select at least one battery pack and measure a voltage of the selected battery pack. When the measured voltage exceeds a predetermined reference voltage, the protection unit  340  may perform the protection operation, e.g., by controlling a switching operation of a charging switch CFET and a discharging DFET of the switch unit  40 . 
     For example, the protection unit  340  may measure a voltage of the selected first battery pack  210  and perform the protection operation when the measured voltage of the first battery pack  210  exceeds the reference voltage. 
     In an implementation, the protection unit  340  may include a reference voltage adjusting unit (not shown) to adjust the reference voltage. 
     The control unit  330  may select at least one of the battery packs or battery cells of the battery  20  and generate the selection control signal CONT 1  to correspond to the selected one, to transmit the selection control signal CONT 1  to the selecting unit  320 . 
     The control unit  330  may generate or determine an actual cell voltage value of the battery cells  211 ,  212 ,  221 ,  222 ,  231 , and  332 , and/or an actual battery pack voltage value of the battery packs  210 ,  220 , and  230 , by allowing for a plurality of voltage drop (first voltage drop to tenth voltage drop) components caused by resistance components of the lines L 1 , L 2 , L 5 , L 6 , L 8 , L 9  (connecting the battery cells  211 ,  212 ,  221 ,  222 ,  231 , and  332 ) and the lines L 3 , L 4 , L 7 , and L 10  (connecting the battery  20  with the protection module  30 ). Each of the voltage drop components may be calculated in advance or may be experimentally measured. 
     The control unit  330  may control charging and discharging operations of the battery  20  using the determined battery cell voltage value and/or battery pack voltage value. For example, the control unit  330  may control the charging switch CFET to control the charging operation when the generated battery cell voltage value or battery pack voltage value is equal to or lower than the reference voltage, and control the discharging switch DFET to control the discharging operation when the determined battery cell voltage value or battery pack voltage value exceeds the reference voltage. 
     In general, when a battery is being charged, the measured voltage is higher than an actual cell voltage or battery pack voltage. Thus, a protection operation may be performed erroneously if it appears that the measured battery pack voltage exceeds the reference voltage. However, when the measured cell or battery cell voltage (as compared to the actual voltage) exceeds the reference voltage, the protection operation is not necessary unless the actual cell or battery cell voltage exceeds the reference voltage. Thus, according to the present example embodiment, the control unit  330  controls the switching operation of the charging switch CFET to disconnect the battery  20  from the charger  50  based on the determined voltage (which allows for a plurality of voltage drop components caused by resistance components of the lines L 1 , L 2 , L 5 , L 6 , L 8 , L 9  and the lines L 3 , L 4 , L 7 , and L 10 ). Thus, the control unit  330  may avoid an erroneous protection operation of the protection unit  340 , which might otherwise be caused by a voltage drop. 
     For example, the control unit  330  may select the first battery pack  210  and measure the voltage of the first battery pack  210 . The control unit  340  may determine the positive electrode potential of the first battery pack  210  by subtracting the third voltage drop caused by the third line L 3  from the measured positive electrode potential. The control unit  330  may determine the negative electrode potential of the first battery pack  210  by adding the fourth voltage drop caused by the fourth line L 4  to the measured negative electrode potential of the first battery pack  210 . The control unit  330  may determine a voltage value of the first battery pack  210  as the difference between the determined positive electrode and the determined negative electrode potential of the first battery pack  212 . 
     If the battery  20  is being charged, the protection unit  340  measures the positive electrode potential as a value obtained by adding the third voltage drop to the actual positive electrode potential of the first battery pack  210  and the negative electrode potential as a value obtained by adding the fourth voltage drop to the actual negative electrode potential of the first battery pack. Accordingly, the protection unit  340  may perform the protection operation when determining that a measured voltage of the first battery pack  210  added with the first voltage drop and the fourth voltage drop exceeds the reference voltage. When the determined voltage value of the first battery pack  210  (which accounts for the voltage drop components) is equal to or lower than the reference value, the protection operation is not necessary. Accordingly, the control unit  330  may avoid an erroneous protection operation of the protection unit  340 , in which charging of the battery  20  is cut off prematurely. 
     In an implementation, the control unit  330  may select the first battery cell  211  and measure the positive electrode potential and the negative electrode potential of the first battery cell  211 . The control unit  330  may determine the positive electrode potential of the first battery cell  211  as a value obtained by subtracting the first voltage drop caused by the first line L 1  and the third voltage drop caused by the third line L 3  from the measured positive electrode potential of the first battery cell  211 . The control unit  330  may determine the negative electrode potential of the first battery cell  211  as a value obtained by adding the second voltage drop caused by the second line L 2  and the fourth voltage drop caused by the fourth line L 4  to the measured negative electrode potential of the first battery cell  211 . The control unit  330  may determine a voltage value of the first battery cell  211  as the difference between the determined positive electrode potential and the determined negative electrode potential of the first battery cell  211 . 
     In an implementation, the control unit  330  may include a reference voltage adjusting unit (not shown) to adjust the reference voltage. 
     In the example embodiment shown in  FIG. 1 , the switch unit  40  includes the charging switch CFET and the discharging switch DFET. The charging switch CFET and the discharging switch DFET are electrically connected to the control unit  330  and the protection unit  340 , and are controlled by the control unit  330  and the protection unit  340 . 
     As described above, the battery protection system  1  may have a measurement unit to perform voltage measuring. The battery protection system  1  may perform measurement using the control unit  330 , e.g., whereby the control unit  330  selects the first battery pack  210  and measures the voltage of the first battery pack  210 , or may perform measurement using the protection unit  340 , e.g., whereby the protection unit  340  measures a voltage of the selected first battery pack  210 ). 
       FIG. 1  illustrates one battery pack including two battery cells connected in parallel for better understanding and ease of description, but other numbers, e.g., three or more, of the battery cells connected in parallel may be included in one battery pack. 
     Also,  FIG. 1  illustrates the battery cells connected by using the first to tenth lines for better understanding and ease of description, but, when three or more battery cells connected in parallel are included in one battery pack, the battery packs may be connected by using a corresponding number of lines. 
       FIG. 2  illustrates a flowchart showing a battery protection method during charging in accordance with another example embodiment. 
     Herein, the detailed structures and corresponding operations of the control unit  330  are the same as described above, and thus redundant descriptions thereof may be omitted. 
     Referring to  FIG. 2 , the control unit  330  selects at least one battery pack and measures a positive electrode potential and a negative electrode potential of the selected battery pack (operation S 10 ). 
     The control unit  330  determines an actual battery pack voltage value by subtracting voltage drops caused by lines connected to the selected battery pack and battery cell from the measured positive and negative electrode potentials of the battery pack (operation S 20 ). 
     The control unit  330  evaluates whether or not the determined battery pack voltage value (which reflects the voltage drops) exceeds a reference voltage, and does not disconnect the battery  20  from the charger  50  if the determined battery pack voltage value is equal to or lower than the reference voltage (operation S 30 ). If the determined battery pack voltage value exceeds the reference voltage, the control unit  330  disconnects the battery  20  from the charger  50  so as to stop charging the battery  20  (operation S 40 ). 
     The operations may repeat as another one battery pack or more are selected and voltages of the selected battery packs are measured. 
     By way of summation and review, efforts are under way to improve battery functions, e.g., not only to increase battery capacity to expand available use time of portable devices, but also to enhance safety in using batteries and precisely measuring battery residual capacity. A battery for a portable device may be manufactured so as to include a plurality of battery cells, various sensors for measuring battery residual capacity and the like, and a protection circuit. However, without consideration of a voltage drop, a malfunction in a protection operation may occur. 
     As described above, embodiments relate to improving accuracy in battery protection by allowing for a voltage drop with respect to a high battery cell voltage (potential) during charging and a voltage drop of a low battery cell voltage during discharging. Embodiments may provide a battery protection system and a battery protection method using the same, having advantages of improving accuracy in voltage measurement of battery cells by allowing for a voltage drop of a parallel structure of the battery cells. Further, embodiments may provide a battery protection system and a battery protection method using the same, having advantages of preventing malfunctions in a battery-cell protection unit. 
     Example embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. In some instances, as would be apparent to one of ordinary skill in the art as of the filing of the present application, features, characteristics, and/or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated. Accordingly, it will be understood by those of skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims. 
     
       
         
           
               
             
               
                   
               
               
                 &lt;Description of Symbols&gt; 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                  1: battery protection system 
                  20: battery 
               
               
                   
                  30: protection module 
                  40: switch unit 
               
               
                   
                  50: charger 
                  60: load 
               
               
                   
                 210: first battery pack 
                 211: first battery cell 
               
               
                   
                 212: second battery cell 
                 220: second battery pack 
               
               
                   
                 221: third battery cell 
                 222: fourth battery cell 
               
               
                   
                 230: third battery pack 
                 231: fifth battery cell 
               
               
                   
                 232: sixth battery cell 
                 311 to 314: measurement terminal 
               
               
                   
                 320: selecting unit 
                 330: control unit 
               
               
                   
                 340: protection unit