Systems and methods for cell balancing

• US 8,957,625 B2
• Filed: 12/13/2012
• Issued: 02/17/2015
• Est. Priority Date: 09/29/2009
• Status: Active Grant

• Current Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Original Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Inventors: Li, Guoxing, Zhang, Wei, Chen, Songtao, Zhang, Chutao
• Primary Examiner(s): Rodas, Richard Isla
• Assistant Examiner(s): PELTON, NATHANIEL R
• Application Number:
  US13/713,944
• Publication Number:
  US 20130099723A1
• Time in Patent Office: 796 Days
• Field of Search: 320/103, 320118-120
• US Class Current: 320/103
• CPC Class Codes: H01M 10/42 Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells H01M10/60 takes precedence
• CPC Class Codes: H01M 10/4207 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 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• 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 for balancing multiple battery cells which are grouped into multiple battery modules includes: obtaining cell parameters of the battery cells, respectively; calculating an average cell parameter for each of the battery modules according to the cell parameters; identifying a donator module and a receiver module from the battery modules based upon the average cell parameter; and transferring energy from the donator module to the receiver module to balance the battery cells.

Claims

1. A method for balancing a battery pack comprising a plurality of battery cells, wherein said method comprises:

accessing a plurality of cell parameters of said plurality of battery cells, wherein said battery cells are logically grouped into a plurality of battery modules that comprise a first battery module including a first number of battery cells and comprise a second battery module including a second number of battery cells, said second number different from said first number;

averaging cell parameters of battery cells in each of said battery modules to obtain an average cell parameter for each of said battery modules;

determining a donator group of battery modules and a receiver group of battery modules from said plurality of battery modules;

identifying a battery module having the maximum average cell parameter among said donator group of battery modules as a donator module;

identifying a battery module having the minimum average cell parameter among said receiver group of battery modules as a receiver module;

transferring energy from said donator module to said receiver module to balance battery cells in said battery pack;

determining a first group of battery modules among said plurality of battery modules according to configurations of a first switch array coupled to said plurality of battery cells; and

determining a second group of battery modules among said plurality of battery modules according to configurations of a second switch array coupled to said plurality of battery cells,

wherein said donator group of battery modules includes said first and second groups.

2. The method as claimed in claim 1, further comprising:

identifying the maximum cell parameter of said plurality of cell parameters,

wherein each battery module in said donator group comprises a battery cell having said maximum cell parameter.

3. The method as claimed in claim 1, further comprising:

identifying the minimum cell parameter of said plurality of cell parameters,

wherein each battery module in said receiver group comprises a battery cell having said minimum cell parameter.

4. The method as claimed in claim 1, further comprising:

determining whether said donator module is selected from said first group or from said second group;

determining that said receiver group includes the battery modules in said first group if said donator module is selected from said second group; and

determining that said receiver group includes the battery modules in said second group if said donator module is selected from said first group.

5. The method as claimed in claim 1, further comprising:

identifying the minimum cell parameter of said plurality of cell parameters;

determining whether said donator module is selected from said first group or from said second group;

determining that said receiver group includes battery modules selected from said first group if said donator module is selected from said second group, wherein each of said selected battery modules from said first group comprises a battery cell having said minimum cell parameter; and

determining that said receiver group includes battery modules selected from said second group if said donator module is selected from said first group, wherein each of said selected battery modules from said second group comprises a battery cell having said minimum cell parameter.

6. The method as claimed in claim 1, wherein said plurality of battery cells comprise a first cell, a second cell and a third cell, wherein said battery modules comprise a first module having said first cell, a second module having said second cell, a third module having said third cell, a fourth module having said first and second cells, a fifth module having said second and third cells, and a sixth module having said first, second and third cells.

11. The method as claimed in claim 1, further comprising:

connecting said donator module to a first winding of a converter; and

subsequent to said connecting of said donator module to said first winding, disconnecting said donator module from said first winding and connecting said receiver module to a second winding of said converter.

7. A system for balancing a plurality of battery cells which are grouped into a plurality of battery modules, said system comprising:

a detection and control unit operable for accessing a plurality of cell parameters of said plurality of battery cells, averaging cell parameters of battery cells in each of said battery modules to obtain an average cell parameter for each of said battery modules, selecting a donator group of battery modules and a receiver group of battery modules from said plurality of battery modules, identifying a battery module having the maximum average cell parameter among said donator group of battery modules as a donator module, identifying a battery module having the minimum average cell parameter among said receiver group of battery modules as a receiver module, and generating control signals, wherein said battery cells are logically grouped into said battery modules, said battery modules comprise a first battery module including a first number of battery cells and comprise a second battery module including a second number of battery cells, and said second number is different from said first number; and

a conversion, circuit coupled to said detection and control unit, operable for transferring energy from said donator module to said receiver module according to said control signals to balance said plurality of battery cells, wherein said conversion circuit comprises;

a first switch array coupled to said plurality of battery cells, wherein a first group of battery modules among said plurality of battery modules is determined according to configurations of said first switch array; and

a second switch array coupled to said plurality of battery cells, wherein a second group of battery modules among said plurality of battery modules is determined according to configurations of said second switch array,

wherein said donator group of battery modules includes the battery modules in said first and second groups.

8. The system as claimed in claim 7, wherein said detection and control unit comprises:

a processing unit operable for determining whether said donator module is selected from said first group or from said second group, for determining that said receiver group includes the battery modules in said first group if said donator module is selected from said second group, and for determining that said receiver group includes the battery modules in said second group if said donator module is selected from said first group.

9. The system as claimed in claim 7, wherein said detection and control unit comprises:

a processing unit operable for identifying the minimum cell parameter of said plurality of cell parameters, for determining whether said donator module is selected from said first group or from said second group, for determining that said receiver group includes battery modules in said first group if said donator module is selected from said second group, wherein each of said battery modules in said receiver group comprises a battery cell having said minimum cell parameter, and for determining that said receiver group includes battery modules in said second group if said donator module is selected from said first group, wherein each of said battery modules in said receiver group comprises a battery cell having said minimum cell parameter.

10. The system as claimed in claim 7, wherein said plurality of battery cells comprise a first cell, a second cell, and a third cell, wherein said battery modules comprise a first module having said first cell, a second module having said second cell, a third module having said third cell, a fourth module having said first and second cells, a fifth module having said second and third cells, and a sixth module having said first, second and third cells.

12. The system as claimed in claim 7, wherein said conversion circuit comprises a first winding and a second winding, and wherein said detection and control unit connects said donator module to said first winding, and subsequent to the connecting of said donator module to said first winding, said detection and control unit disconnects said donator module from said first winding and connects said receiver module to said second winding.

13. A method for balancing a battery pack comprising a plurality of battery cells, wherein said method comprises:

accessing a plurality of cell parameters of said plurality of battery cells, wherein said battery cells are logically grouped into a plurality of battery modules that comprise a first battery module including a first number of battery cells and comprise a second battery module including a second number of battery cells, said second number different from said first number;

averaging cell parameters of battery cells in each of said battery modules to obtain an average cell parameter for each of said battery modules;

determining a donator group of battery modules and a receiver group of battery modules from said plurality of battery modules;

identifying a battery module having the maximum average cell parameter among said donator group of battery modules as a donator module;

identifying a battery module having the minimum average cell parameter among said receiver group of battery modules as a receiver module;

transferring energy from said donator module to said receiver module to balance battery cells in said battery pack;

determining a first group of battery modules among said plurality of battery modules according to configurations of a first switch array coupled to said plurality of battery cells; and

determining a second group of battery modules among said plurality of battery modules according to configurations of a second switch array coupled to said plurality of battery cells,

wherein said receiver group of battery modules includes the battery modules in said first and second groups.

14. The method as claimed in claim 13, further comprising:

determining whether said receiver module is selected from said first group or from said second group;

determining that said donator group includes the battery modules in said first group if said receiver module is selected from said second group; and

determining that said donator group includes the battery modules in said second group if said receiver module is selected from said first group.

15. The method as claimed in claim 13, further comprising:

identifying the maximum cell parameter of said plurality of cell parameters;

determining whether said receiver module is selected from said first group or from said second group;

determining that said donator group includes battery modules selected from said first group if said receiver module is selected from said second group, wherein each of said selected battery modules from said first group comprises a battery cell having said maximum cell parameter; and

determining that said donator group includes battery modules selected from said second group if said receiver module is selected from said first group, wherein each of said selected battery modules from said second group comprises a battery cell having said maximum cell parameter.

16. The method as claimed in claim 13, further comprising:

connecting said donator module to a first winding of a converter; and

subsequent to said connecting of said donator module to said first winding, disconnecting said donator module from said first winding and connecting said receiver module to a second winding of said converter.

17. A system for balancing a plurality of battery cells which are grouped into a plurality of battery modules, said system comprising:

a detection and control unit operable for accessing a plurality of cell parameters of said plurality of battery cells, averaging cell parameters of battery cells in each of said battery modules to obtain an average cell parameter for each of said battery modules, selecting a donator group of battery modules and a receiver group of battery modules from said plurality of battery modules, identifying a battery module having the maximum average cell parameter among said donator group of battery modules as a donator module, identifying a battery module having the minimum average cell parameter among said receiver group of battery modules as a receiver module, and generating control signals, wherein said battery cells are logically grouped into said battery modules, said battery modules comprise a first battery module including a first number of battery cells and comprise a second battery module including a second number of battery cells, and said second number is different from said first number; and

a conversion, circuit coupled to said detection and control unit, operable for transferring energy from said donator module to said receiver module according to said control signals to balance said plurality of battery cells, wherein said detection and control unit comprises;

a first switch array coupled to said plurality of battery cells, wherein a first group of battery modules among said plurality of battery modules is determined according to configurations of said first switch array; and

a second switch array coupled to said plurality of battery cells, wherein a second group of battery modules among said plurality of battery modules is determined according to configurations of said second switch array,

wherein said receiver group of battery modules includes the battery modules in said first and second groups.

18. The system as claimed in claim 17, wherein said detection and control unit comprises:

a processing unit operable for determining whether said receiver module is selected from said first group or from said second group, for determining that said donator group includes the battery modules in said first group if said receiver module is selected from said second group, and for determining that said donator group includes the battery modules in said second group if said receiver module is selected from said first group.

19. The system as claimed in claim 17, wherein said detection and control unit comprises:

a processing unit operable for identifying the maximum cell parameter of said plurality of cell parameters, for determining whether said receiver module is selected from said first group or from said second group, for determining that said donator group includes the battery modules in said first group if said receiver module is selected from said second group, and for determining that said donator group includes the battery modules in said second group if said receiver module is selected from said first group, wherein each of said battery modules in said donator group comprises a battery cell having said maximum cell parameter.

20. The system as claimed in claim 17, wherein said conversion circuit comprises a first winding and a second winding, and wherein said detection and control unit connects said donator module to said first winding, and subsequent to the connecting of said donator module to said first winding, said detection and control unit disconnects said donator module from said first winding and connects said receiver module to said second winding.