Protective circuit for a rechargeable battery pack

• US 9,267,998 B2
• Filed: 12/24/2012
• Issued: 02/23/2016
• Est. Priority Date: 12/22/2011
• Status: Active Grant

• Current Assignee: Andreas STIHL AG & Company KG (Stihl Holding AG & Company KG)
• Original Assignee: Andreas STIHL AG & Company KG (Stihl Holding AG & Company KG)
• Inventors: Gaul, Henrik, Schurr, Martin
• Primary Examiner(s): Nguyen, Danny
• Application Number:
  US13/726,366
• Publication Number:
  US 20130162052A1
• Time in Patent Office: 1,156 Days
• Field of Search: 307115-116
• US Class Current: 1/1
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• CPC Class Codes: G01R 31/385 Arrangements for measuring battery or accumulator variables for monitoring G01R31/382
• CPC Class Codes: G01R 31/396 Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
• CPC Class Codes: G01R 31/40 Testing power supplies testing photovoltaic devices H02S50/10
• CPC Class Codes: H01H 47/002 Monitoring or fail-safe circuits
• 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: H01M 2010/4271 Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
• CPC Class Codes: H01M 50/51 Connection only in series
• CPC Class Codes: H02H 7/18 for batteries; for accumulators
• CPC Class Codes: H02J 7/00304 Overcurrent protection
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A protective circuit for an arrangement which includes a plurality of individual cells in a rechargeable battery pack with a predefined number of individual cells being connected in series in a cell row and at least two cell rows being situated parallel to one another. The component current flowing in a first cell row when the rechargeable battery pack is subject to loading is compared with the component current flowing in a second cell row to generate a signal when there is an implausible deviation in the component currents with respect to one smother. The signal is used to disconnect a defective cell row or to switch off the entire rechargeable battery pack in order to protect the latter.

Claims

1. A protective circuit for an arrangement having a plurality of individual cells in a rechargeable battery pack, wherein a predetermined number of individual cells are connected in series so as to form a cell row and at least a first and a second cell row are arranged in parallel;

the first cell row is configured to have a first component current flow therein when a load is applied to the battery pack and the second cell row is configured to have a second component current flow therein when a load is applied to the battery pack, said protective circuit comprising;

a circuit device configured to compare the first component current with the second component current to determine whether an implausible deviation is present therebetween and generate a signal when an implausible deviation is present;

each of said cell rows having a plurality of cell blocks arranged in series;

each of said cell blocks having at least two individual cells arranged in parallel; and

,

said circuit device being configured to standardize said first and second component currents detected with the number of individual cells arranged in parallel in the corresponding one of said cell rows.

2. The protective circuit of claim 1, wherein:

said circuit device is configured to calculate a difference between the first and the second component currents and generate said signal when said difference exceeds a pregiven value (I_G).

3. The protective circuit of claim 1, wherein said circuit device is configured to standardize said first component current and said second component current before comparing said currents;

and, said circuit device is configured so as to cause said signal to be generated when said difference exceeds a predetermined value (I_G).

4. The protective circuit of claim 1, wherein said implausible deviation is derived from the ratio (v) of said first and said second component currents to each other.

5. The protective circuit of claim 1, wherein said implausible deviation is derived from a change of the mathematical sign of said component currents.

6. The protective circuit of claim 1, wherein:

said battery pack is configured to output a total current (I_G); and

,

said circuit device is configured to derive said implausible deviation by comparing a sum of the magnitudes of said component currents to said total current (I_G).

7. The protective circuit of claim 1, wherein:

said battery pack has more than two parallel cell rows; and

,

said circuit device is configured to compare said component currents of each of said cell rows to each other.

8. A protective circuit for an arrangement having a plurality of individual cells in a rechargeable battery pack, wherein a predetermined number of individual cells are connected in series so as to form a cell row and at least a first and a second cell row are arranged in parallel;

the first cell row is configured to have a first component current flow therein when a load is applied to the battery pack and the second cell row is configured to have a second component current flow therein when a load is applied to the battery pack, said protective circuit comprising;

a circuit device configured to compare the first component current with the second component current to determine whether an implausible deviation is present therebetween and generate a signal when an implausible deviation is present;

said circuit device being configured to determine a maximum component current (I_max) from said component currents detected; and

,

said circuit device being also configured to determine a difference current (Δ

I_i) between said maximum component current (I_max) and said component currents detected and compare at least one difference current (Δ

I_i) with a limit value (I_G).

9. A protective circuit for an arrangement having a plurality of individual cells in a rechargeable battery pack, wherein a predetermined number of individual cells are connected in series so as to form a cell row and at least a first and a second cell row are arranged in parallel;

the first cell row is configured to have a first component current flow therein when a load is applied to the battery pack and the second cell row is configured to have a second component current flow therein when a load is applied to the battery pack, said protective circuit comprising;

a circuit device configured to compare the first component current with the second component current to determine whether an implausible deviation is present therebetween and generate a signal when an implausible deviation is present;

an evaluation unit; and

, wherein;

said circuit device is configured to output measurement values of said first and said second component currents to said evaluation unit; and

,

said evaluation unit is configured to conduct a plausability test and to determine whether an implausible deviation is present and to output an output signal when an implausible deviation is present.

10. The protective circuit of claim 9, wherein each of said cell rows has an associated switch configured to be controlled by said evaluation unit.

11. The protective circuit of claim 10, wherein:

said circuit device is configured to detect the voltage drops at said switches and output the detected voltage drops to said evaluation unit; and

,

said evaluation unit is configured to evaluate the voltage drop at said switches as a proportional variable to said component currents.

12. The protective circuit of claim 11, wherein said switches are electronic switches.

13. The protective circuit of claim 11, wherein said switches are MOSFETs.

14. A protective circuit for an arrangement having a plurality of individual cells in a rechargeable battery pack, wherein a predetermined number of individual cells are connected in series so as to form a cell row and at least a first and a second cell row are arranged in parallel;

the first cell row is configured to have a first component current flow therein when a load is applied to the battery pack and the second cell row is configured to have a second component current flow therein when a load is applied to the battery pack, said protective circuit comprising;

a circuit device configured to compare the first component current with the second component current to determine whether an implausible deviation is present therebetween and generate a signal when an implausible deviation is present;

an evaluation unit;

said individual cells of each of said cell rows have respective cell connectors arranged between each other;

each of said cell connectors of one cell row having a position therein which corresponds to the position of a corresponding one of the cell connectors in each of the other cell rows;

a plurality of compensation lines electrically interconnecting corresponding ones of the cell connectors of the different rows;

each of said cell connectors being at a potential (U_nl, U_nr); and

,

said circuit device being configured to detect said potential (U_nl) at at least one of said cell connectors of said first cell row and said potential (U_nr) at the corresponding one of said cell connectors of said second row and output said potentials (U_nl, U_nr) to said evaluation unit.

15. The protective circuit of claim 14, wherein said evaluation unit is configured to evaluate said potentials (U_nl, U_nr) with respect to each other and output a signal in dependence on the result of said evaluation.

16. The protective circuit of claim 15, wherein said evaluation unit is configured to compare said potentials (U_nl, U_nr) directly to each other.

17. The protective circuit of claim 14, wherein said evaluation unit is configured to derive a difference voltage (Δ

U) from said potential (U_nl) at said one of said cell connectors of said first cell row and said potential (U_nr) at said corresponding one of said cell connectors of said second cell row and to compare said differential voltage (Δ

U) to a predetermined limit value and to output a signal when said differential voltage (Δ

U) exceeds said limit value.

18. The protective circuit of claim 15, wherein:

said battery pack has a housing;

said cell rows are arranged in said housing;

said evaluation unit is disposed in said housing; and

,

said circuit device is configured to transmit said potential (U_nl) detected at at least one of said cell connectors of said first cell row and said potential (U_nr) at the corresponding one of said cell connectors of said second row to said evaluation unit.

19. The protective circuit of claim 14, wherein:

said battery pack has a plurality of cell rows arranged in parallel;

each one of said cell rows has a multiplicity of individual cells connected in series via the cell connectors corresponding to said one row;

each of said individual cells and cell connectors of one of said cell rows has corresponding ones of individual cells and cell connectors in each of said other cell rows; and

,

each one of said compensation lines interconnects corresponding ones of said cell connectors at like locations in corresponding ones of said cell rows.

20. The protective circuit of claim 19, wherein:

said cell rows include said first cell row and a last cell row connected in parallel with said first cell row;

the cell connectors of said first cell row each have a potential (U_nl);

said cell connectors of said last cell row each have a potential (U_nr);

said circuit device is configured to detect said potentials (U_nl) at said cell connectors of said first cell row and said potentials (U_nr) at said cell connectors of said second cell row and output said potentials to said evaluation unit; and

,

said evaluation unit is configured to evaluate said potentials (U_nl, U_nr).

21. The protective circuit of claim 14, wherein:

said parallel cell rows of said individual cells are configured to form an imaginary matrix having m-rows of individual cells and n-columns of cell rows;

said circuit device is configured to determine a defect by row (m) by comparing said potentials of said cell connectors and to determine a defect by column (n) as a result of the implausible deviation determination.

22. The protective circuit of claim 21, wherein:

each of said cell rows has an associated switch configured to be controlled by said evaluation unit; and

,

said switches are configured to turn off said cell row in which a defect has been determined.

23. The protective circuit of claim 22, wherein:

each of said cell rows has an associated switch configured to be controlled by said evaluation unit;

said signal is a control signal; and

,

said switches are configured to disconnect at least one of said cell rows or said rechargeable battery pack on the basis of said control signal.

24. A protective circuit for an arrangement having a plurality of individual cells in a rechargeable battery pack, wherein a predetermined number of individual cells are connected in series so as to form a cell row and at least a first and a second cell row are arranged in parallel;

the first cell row is configured to have a first component current flow therein when a load is applied to the battery pack and the second cell row is configured to have a second component current flow therein when a load is applied to the battery pack, said protective circuit comprising;

a circuit device configured to compare the first component current with the second component current;

first and second switches arranged in corresponding ones of said first and second cell rows with first and second voltage drops being present across corresponding ones of said first and second switches; and

,

an evaluation unit configured to control said first and second switches and to detect and evaluate said voltage drops as respective quantities proportional to corresponding ones of said first and second component current flows and generating a signal when there is an implausible deviation of said first and second component current flows from each other.