Method and Apparatuses for Determining a State of Charge

• US 20150212160A1
• Filed: 01/21/2015
• Published: 07/30/2015
• Est. Priority Date: 01/30/2014
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Marsili, Stefano, Unterrieder, Christoph
• Granted Patent: US 9,897,657 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/3835 involving only voltage measurements

Abstract

Methods and apparatuses for determining a state of charge of a battery are provided, wherein measurements of a terminal voltage of the battery and stored precharacterization parameters are used for determining the state of charge.

Claims

1. A method, comprising:

detecting a state with low current load of a battery;

detecting a terminal voltage of the battery in the state with low current load, before the terminal voltage reaches a steady state; and

determining a state of charge of the battery based on;

(a) the detected terminal voltage in the state with low current load and (b) a precharacterization parameter which is stored for a respective type of battery.

2. The method of claim 1, wherein the precharacterization parameter describes a relaxation behavior of the battery.

3. The method of claim 2, wherein the precharacterization parameter describes a voltage difference in the case of relaxation between a first time and a second time.

4. The method of claim 3, wherein the first time is between 50 s and 200 s, and the second time is between 1 h and 4 h.

5. The method of claim 1, wherein the precharacterization parameter is selected from a set of stored precharacterization parameters depending on a state parameter which describes a state of the battery.

6. The method of claim 5, further comprising scaling at least one of the stored precharacterization parameters based on the state parameter.

7. The method of claim 5, wherein the state parameter comprises a parameter selected from the group consisting of a temperature, a state of charge, a previous battery current and a duration of a previous battery current.

8. The method of claim 1, wherein determining the state of charge comprises correcting the detected terminal voltage depending on the precharacterization parameter and determining the state of charge depending on the corrected terminal voltage.

9. The method of claim 8, wherein the correction is performed depending on a difference between the precharacterization parameter and an accumulated value for a voltage difference between a plurality of measurements of the terminal voltage.

10. The method of claim 1, further comprising detecting at least one previous parameter describing a history of the battery prior to the state of low current load, wherein the determination of the state of charge is further based on the at least one previous parameter.

11. The method of claim 10, wherein the at least one previous parameter comprises a voltage across the battery and/or a battery current of the battery in a charging or discharging state prior to the state of low current load.

12. The method of claim 1, wherein the precharacterization parameter comprises an increment of an estimator for implementing extrapolation of the measured terminal voltage of the battery.

13. An apparatus, comprising:

a detection apparatus configured to detect a terminal voltage of a battery;

a memory configured to store a precharacterization parameter; and

an evaluation apparatus configured to determine a state of charge of the battery based on (a) the terminal voltage detected by the detection apparatus and (b) an item of precharacterization information stored in the memory.

14. The apparatus of claim 13, wherein the precharacterization parameter describes a relaxation behavior of the battery.

15. The apparatus of claim 14, wherein the precharacterization parameter describes a voltage difference in the case of relaxation between a first time and a second time.

16. The apparatus of claim 13, wherein the evaluation apparatus is configured to select the precharacterization parameter from a set of precharacterization parameters stored in the memory depending on a state parameter which describes a state of the battery.

17. The apparatus of claim 16, wherein the state parameter comprises at least one parameter selected from the group consisting of a temperature, a state of charge, a previous battery current and a duration of a previous battery current.

18. The apparatus of claim 13, wherein the evaluation apparatus is configured to implement correction of the detected terminal voltage depending on the precharacterization parameter and determination of the state of charge depending on the corrected terminal voltage in order to determine the state of charge.

19. The apparatus of claim 18, wherein the correction is performed depending on a difference between the precharacterization parameter and an accumulated value of a voltage difference between a plurality of measurements of the terminal voltage.

20. The apparatus of claim 13, further comprising a further detection apparatus configured to detect at least one previous parameter which describes a history of the battery prior to the state of low current load, wherein the determination of the state of charge takes place depending on the at least one previous parameter.