Method for monitoring the status of a plurality of battery cells in a battery pack

Abstract

The invention relates to a method for monitoring the status of a plurality of battery cells (C1-C5) in a battery pack (1), said method comprising: arranging said battery cells (C1-C5) in at least two groups (G1-G3) of cells; connecting said groups (G1-G3) of cells to a sensor unit (7b); and obtaining, by means of said sensor unit (7b), at least one sensor measurement (U1sens, U2sens, U3sens) for each group (G1-G3) which is indicative of the state of operation of said battery pack (7a). The method according to the invention further comprises: determining a cell measurement (U1cell, U2cell, . . . ) for each battery cell (C1-C5) by means of an over-determined equation system which defines said cell measurement (U1cell, U2cell, . . . ) as a function of said sensor measurement (U1sens, U2sens, U3sens); and evaluating any residual terms resulting from said equation system in order to identify any battery 1 cell having a cell measurement (Ucell) which deviates from an expected value based on the remaining battery cells. The invention also relates to a battery management system (12) for monitoring the status of a plurality of connected battery cells (C1-C5) as mentioned above.

1 - 14 . (canceled) 
     
     
         15 . A method for monitoring the status of a plurality of battery cells in a battery pack, said method comprising:
 arranging said battery cells in at least two groups of cells;   connecting each of said groups of cells to a corresponding sensor of a sensor unit; and   obtaining, by means of said sensor unit, at least one sensor measurement for each group which is indicative of the state of operation of said battery pack;   determining a cell measurement for each battery cell by means of solving an over-determined equation system of equations which defines said cell measurement as a function of said sensor measurement; and   evaluating any residual terms resulting from said equation system in order to identify any battery cell having a cell measurement which deviates from an expected value based on the remaining battery cells.   
     
     
         16 . Method according to  claim 15 , wherein said method further comprises: 
       determining cell measurements corresponding to said residual terms by means of a recalculation of said over-determined equation system using information from the previous calculation of said equation system. 
     
     
         17 . Method according to  claim 16 , wherein said method further comprises:
 providing said residual terms based on a comparison of a cell measurement with an average value of the cell measurements from the equation system.   
     
     
         18 . Method according to  claim 15 , wherein said method further comprises:
 obtaining, by means of said sensor unit, said at least one sensor measurement in the form of a terminal voltage measurement of each battery cell or a temperature measurement of each battery cell.   
     
     
         19 . Method according to  claim 15 , wherein the method further comprises:
 arranging said groups of cells in a manner so that:
 at least two of said groups comprise two or more cells, and 
 at least two of said groups overlap so that a cell forms part of said overlapping groups; and 
   connecting said sensor unit to said groups; and wherein   the number of groups is less than the number of cells.   
     
     
         20 . Method according to  claim 19 , further comprising:
 arranging said groups of cells in a manner so that it fulfills the relationship:
   number of groups−number of cells/2≥1.
 
   
     
     
         21 . A battery management system for monitoring the status of a plurality of connected battery cells in a battery pack, comprising:
 at least two groups of said plurality of cells;   a sensor unit connected to each of said groups, wherein each of said groups is connected to a corresponding sensor forming part of said sensor unit, said sensor unit being configured for providing at least one sensor measurement for each group which is indicative of the state of operation of said battery pack; wherein the battery management system further comprises a battery control unit to which said sensor unit is connected, said battery control unit being configured for determining a cell measurement for each battery cell by means of solving an over-determined equation system of equations which defines said cell measurement as a function of said sensor measurement; wherein said battery control unit is also configured for evaluating any residual terms resulting from said equation system in order to identify any battery cell having a cell measurement which deviates from an expected value based on the remaining battery cells.   
     
     
         22 . A battery management system according to  claim 21 , further comprising:
 an arrangement of said groups of cells wherein:
 at least two of said groups comprise two or more cells, and 
 at least two of said groups overlap so that a cell forms part of said overlapping groups; and 
   a connection between said sensor unit and said groups; wherein   the number of groups is less than the number of cells.   
     
     
         23 . A battery management system according to  claim 21 , wherein said sensors (S 1 -S 3 ) are configured for measuring at least one parameter related to the state of operation of said battery cells (C 1 -C 5 ), said parameter being at least one of the following: the terminal voltage (V) of at least one battery cell; and the temperature (T) of at least one battery cell. 
     
     
         24 . A vehicle comprising a battery management system according to  claim 21 . 
     
     
         25 . A computer program comprising program code means for performing the method steps of  claim 15  when said program is run on a computer. 
     
     
         26 . A non-transitory computer readable medium carrying a computer program comprising program code means for performing the steps of  claim 15  when said program product is run on a computer. 
     
     
         27 . A control unit for monitoring the status of a plurality of connected battery cells in a battery pack, the control unit being configured to perform the steps of the method according to  claim 15 .