Method and apparatus for identifying and disconnecting short-circuited battery cells within a battery pack

• US 7,683,575 B2
• Filed: 07/18/2007
• Issued: 03/23/2010
• Est. Priority Date: 07/18/2007
• Status: Active Grant

• Current Assignee: Tesla Inc.
• Original Assignee: Tesla Motors Incorporated (Tesla Inc.)
• Inventors: Kohn, Scott Ira, Berdichevsky, Eugene Michael, Kelty, Kurt Russell
• Primary Examiner(s): Tso; Edward
• Assistant Examiner(s): HERNANDEZ, MANUEL J
• Application Number:
  US11/779,620
• Publication Number:
  US 20090023053A1
• Time in Patent Office: 979 Days
• Field of Search: 320/132, 320/133, 320/122, 320/127
• US Class Current: 320/122
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: H01M 10/425 Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing printed circuits H05K1/00
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/482 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H02J 2310/48 for electric vehicles [EV] or hybrid vehicles [HEV]
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/0031 using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A method and apparatus for deactivating a bad battery cell from a battery pack for an energy storage system of an electric vehicle is disclosed. The apparatus and methodology includes a clamshell member arranged at an end of the cells and a printed circuit board arranged adjacent to the clamshell member. A collector plate is arranged adjacent to the printed circuit board and a switch is arranged on the printed circuit board. A wire bond is arranged between the switch and one of the cells and a second wire bond is arranged between the switch and the collector plate. The plurality of switches will allow for the identification of the one individual cell having a weak short circuit within the battery pack. Upon identification of the cell with the weak short circuit that cell will have its switch placed in an open position thus electrically isolating the faulty or bad cell from the battery pack.

Claims

1. A method of identifying and selectively disconnecting a faulty battery cell within a battery pack comprised of a plurality of cells, said method comprising the steps of:

monitoring at least one performance parameter of a group of cells within said plurality of cells;

comparing said at least one performance parameter to a range of acceptable values for said at least one performance parameter, wherein operation of said group of cells outside of said range of acceptable values indicates a short circuit within said group of cells; and

determining if said group of cells is operating within said range of acceptable values and if said group of cells is operating outside of said range of acceptable values, performing the steps of;

temporarily disconnecting each cell, one by one, of said group of cells while monitoring said at least one performance parameter of said group of cells and comparing said at least one performance parameter to said range of acceptable values, wherein said step of temporarily disconnecting each cell is performed by operating a switch of a plurality of switches corresponding to the cell being temporarily disconnected, wherein each switch of said plurality of switches corresponds to each cell of said group of cells, and wherein each switch is interposed between said corresponding cell of said group of cells and a common collector element; and

permanently disconnecting said faulty battery cell from the group of cells when said group of cells operates outside of said range of acceptable values during said temporary disconnecting step, wherein said permanent disconnecting step is performed by permanently operating said corresponding switch.

2. The method of claim 1 wherein said step of monitoring said at least one performance parameter of said group of cells further comprise the step of monitoring a self discharge rate for said group of cells.

3. The method of claim 1 wherein said step of monitoring said at least one performance parameter of said group of cells further comprise the step of monitoring a length of time required to perform a resistive balancing operation on said group of cells.

4. The method of claim 1 wherein said steps of monitoring said at least one performance parameter of said group of cells further comprise the step of monitoring a quantity of energy required during voltage balancing.

5. The method of claim 1 wherein operating said switch causes said switch to change between a closed state and an open state.

6. The method of claim 1 wherein operating said switch causes said switch to remain in an open state.

7. The method of claim 1 wherein said switch is a transistor.

8. An apparatus for selectively disconnecting a faulty battery cell within a battery pack comprised of a plurality of cells, said apparatus comprising:

a plurality of switches, wherein each switch of said plurality of switches corresponds to each cell of said plurality of cells, and wherein activation of a particular switch of said plurality of switches disconnects a corresponding cell of said plurality of cells from said battery pack;

a first wire bond arranged between each switch of said plurality of switches and said corresponding cell of said plurality of cells;

a second wire bond arranged between each switch of said plurality of switches and a common collector plate;

means for testing said plurality of cells to determine if a short circuit exists within said plurality of cells;

means for sequentially and temporarily disconnecting each cell of said plurality of cells by operating each switch of said plurality of switches if a short circuit is determined to exist within said plurality of cells, wherein operation of each switch of said plurality of switches causes said corresponding cell to be disconnected from said plurality of cells;

means for monitoring operation of said plurality of cells while sequentially and temporarily disconnecting each cell of said plurality of cells to identify said faulty battery cell within said plurality of cells; and

means for permanently operating said switch of said plurality of switches corresponding to said faulty battery cell, wherein said faulty battery cell is permanently disconnected from said group of cells.

9. The apparatus of claim 8 wherein a processor comprises said testing means, said sequential and temporary disconnecting means, and said permanent operating means.

10. The apparatus of claim 8 further comprising a printed circuit board, wherein each switch of said plurality of switches is mounted to said printed circuit board.

11. The apparatus of claim 8 wherein operating a particular switch of said plurality of switches causes said switch to change between a closed state and an open state.

12. The apparatus of claim 8 wherein said plurality of switches are normally in an open state, and wherein operating a particular switch of said plurality of switches causes said switch to remain in an open state.