Steady state detection of an exceptional charge event in a series connected battery element

• US 9,153,990 B2
• Filed: 11/30/2012
• Issued: 10/06/2015
• Est. Priority Date: 11/30/2012
• Status: Active Grant

• Current Assignee: Tesla Inc.
• Original Assignee: Tesla Motors Incorporated (Tesla Inc.)
• Inventors: LePort, Francisco, Kohn, Scott Ira
• Primary Examiner(s): TSO, EDWARD H
• Application Number:
  US13/690,105
• Publication Number:
  US 20140152258A1
• Time in Patent Office: 1,040 Days
• Field of Search: 320/107, 320/116, 320/118, 320/119, 320/128, 320/134, 320/136
• US Class Current: 1/1
• CPC Class Codes: H02J 7/00036 Charger exchanging data with battery
• CPC Class Codes: H02J 7/00047 with provisions for charging different types of batteries
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: H02J 7/00309 Overheat or overtemperature protection
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A system and method for identifying and responding to exceptional charge events of series-connected energy storage elements. An exceptional charge event detector for an energy storage system having a plurality of series-connected battery elements, comprising: a data acquisition system determining, for each battery element of the plurality of series-connected battery elements, a series of charge dependent parameters during an operational period of the energy storage system; a controller, coupled to said data acquisition system, establishing a characterization for each battery element of the plurality of series-connected battery elements from said series of charge dependent parameters; wherein said characterization includes either a normal characteristic pattern or an exceptional characteristic pattern for each time segment of a plurality of time segments spanning said operational period; and wherein said controller detects an exceptional charge event for a selected one battery element whenever said characterization for said selected one battery element includes an exceptional characteristic pattern in any particular time segment where a normal characteristic pattern is expected.

Claims

1. An exceptional charge event detector for an energy storage system having a plurality of series-connected battery elements, comprising:

a data acquisition system determining, for each battery element of the plurality of series-connected battery elements, a series of charge dependent parameters during an operational period of the energy storage system;

a controller, coupled to said data acquisition system, establishing a characterization for each battery element of the plurality of series-connected battery elements from said series of charge dependent parameters;

wherein said characterization includes either a normal characteristic pattern or an exceptional characteristic pattern for each time segment of a plurality of time segments spanning said operational period; and

wherein said controller detects an exceptional charge event for a selected one battery element whenever said characterization for said selected one battery element includes an exceptional characteristic pattern in any particular time segment where a normal characteristic pattern is expected.

2. The exceptional charge event detector of claim 1 wherein said operation includes charging the energy storage system from a charging station with said exceptional charge event indicating an overcharge of the selected battery element.

3. The exceptional charge event detector of claim 2 wherein said series of parameters for said selected battery element include a voltage level during each of said time segments.

4. The exceptional charge event detector of claim 3 wherein said characterization of said selected battery element includes a determination of a change in said battery voltage level versus a change in a charge of said selected battery element over a particular time segment.

5. The exceptional charge event detector of claim 4 wherein said normal charge pattern includes a substantially linear characteristic for said determination and wherein said exceptional charge pattern includes a substantially non-linear characteristic for said determination.

6. The exceptional charge detector of claim 1 including a reference determined from said series of charge dependent parameters for a group of the plurality of battery elements.

7. The exceptional charge detector of claim 6 with said characteristic patterns for each particular time segment for each particular battery elements includes a difference between said reference and said parameter for said particular battery element in said particular time segment.

8. The exceptional charge event detector of claim 7 wherein said operation includes charging the energy storage system from a charging station.

9. The exceptional charge event detector of claim 8 wherein said series of parameters for a particular battery element include a voltage level for the particular battery element during each of said time segments.

10. The exceptional charge event detector of claim 9 wherein said characterization for a particular battery element includes a determination of a change in said battery voltage level for a change in a charge of said particular battery element over a particular time segment.

11. The exceptional charge event detector of claim 10 wherein said normal charge pattern includes a substantially linear characteristic for said determination and wherein said exceptional charge pattern includes a substantially non-linear characteristic for said determination.

12. The exceptional charge event detector of claim 1 wherein said operation includes discharging the energy storage system.

13. The exceptional charge event detector of claim 12 wherein said series of parameters for a particular battery element include a voltage level for the particular battery element during each of said time segments.

14. The exceptional charge event detector of claim 13 wherein said characterization for a particular battery element includes a determination of a change in said battery voltage level for a change in a charge of said particular battery element over a particular time segment.

15. The exceptional charge event detector of claim 14 wherein said normal charge pattern includes a substantially linear characteristic for said determination and wherein said exceptional charge pattern includes a substantially non-linear characteristic for said determination.

16. The exceptional charge detector of claim 12 including a reference determined from said series of charge dependent parameters for a group of the plurality of battery elements.

17. The exceptional charge detector of claim 16 with said characteristic patterns for each particular time segment for each particular battery elements includes a difference between said parameter for said particular battery element in said particular time segment and said reference.

18. The exceptional charge event detector of claim 17 wherein said operation includes charging the energy storage system from a charging station.

19. The exceptional charge event detector of claim 18 wherein said series of parameters for a particular battery element include a voltage level for the particular battery element during each of said time segments.

20. The exceptional charge event detector of claim 19 wherein said characterization for a particular battery element includes a determination of a change in said battery voltage level for a change in a charge of said particular battery element over a particular time segment.

21. The exceptional charge event detector of claim 20 wherein said normal charge pattern includes a substantially linear characteristic for said determination and wherein said exceptional charge pattern includes a substantially non-linear characteristic for said determination.

22. The exceptional charge event detector of claim 1 wherein said data acquisition system includes a voltage measurement and balancing system establishing and reducing a voltage mismatch between voltage levels of the plurality of battery elements.

23. A rechargeable energy storage system having a plurality of series-connected lithium-ion battery elements, comprising:

a voltage measurement and balancing system detecting and reducing voltage imbalances between voltage levels of the plurality of battery elements of the energy storage system wherein said voltage measurement and balancing system uses a first detection modality to determine an existence of a voltage imbalance; and

an exceptional charge event detector monitoring the plurality of battery elements for an exceptional charge event using a second detection modality different from said first detection modality;

wherein said exceptional charge event detector determines, for each battery element of the plurality of battery elements, a series of charge dependent parameters during an operational period of the energy storage system, and further comprising;

a controller establishing a characterization for each battery element of the plurality of series-connected battery elements from said series of charge dependent parameters;

wherein said characterization includes either a normal characteristic pattern or an exceptional characteristic pattern for each time segment of a plurality of time segments spanning said operational period; and

with said controller detecting an exceptional charge event for a selected one battery element whenever said characterization for said selected one battery element includes an exceptional characteristic pattern in any particular time segment where a normal characteristic pattern is expected.

24. A computer-implemented method for detecting an exceptional charge event for an energy storage system having a plurality of series-connected battery elements, comprising:

a) determining, for each battery element of the plurality of series-connected battery elements, a series of charge dependent parameters during an operational period of the energy storage system;

b) establishing a characterization for each battery-element of the plurality of seris-connected battery elements from said series of charge dependent parameters;

wherein said characterization includes either a normal characteristic pattern or an exceptional characteristic pattern for each time segment of a plurality of time segments spanning said operational period; and

c) detecting an exceptional charge event for a selected one battery element whenever said characterization for said selected one battery element includes an exceptional characteristic pattern in any particular time segment where a normal characteristic pattern is expected.