Method of adjusting SOC for battery and battery management system using the same

• US 20070148532A1
• Filed: 12/19/2006
• Published: 06/28/2007
• Est. Priority Date: 12/22/2005
• Status: Active Grant

• Current Assignee: Samsung SDI Company Limited
• Original Assignee: Samsung SDI Company Limited
• Inventors: Seo, Se-Wook, Lim, Gye-Jong, Yun, Han-Seok
• Granted Patent: US 7,982,433 B2
• Time in Patent Office: Days
• US Class Current: 429/50
• CPC Class Codes: G01R 31/3828 using current integration
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• 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 state of charge (SOC) compensation method of a battery and a battery management system using the same. A charge/discharge current of the battery is used for calculating the SOC and an SOC voltage that is a value in an OCV table, a rheobasic voltage is calculated, an error in the SOC is measured by using a difference between the SOC voltage and the rheobasic voltage, and a range of the error is determined among multiple effective ranges. Subsequently, the SOC is compensated by using a compensation SOC set in correspondence with a range in which the error is included to thereby measure a more accurate SOC of the battery.

Claims

1. A state of charge (SOC) compensation method of a battery management system for compensating an SOC of a battery, the SOC compensation method comprising:

calculating the SOC of the battery and an SOC voltage corresponding to the SOC by using a charge/discharge current of the battery;

calculating a rheobasic voltage of the battery by using the charge/discharge current of the battery, a voltage of the battery, and an internal resistance of the battery;

calculating an integration error corresponding to a difference between the SOC voltage and the rheobasic voltage;

determining in which effective range the integration error is included among multiple effective ranges; and

adding a compensation SOC corresponding to the effective range in which the integration error is included among the multiple effective ranges to the SOC to make a compensated SOC included in an SOC range that corresponds to a minimum effective range among the multiple effective ranges.

2. The SOC compensation method of claim 1, wherein said determining in which effective range comprises comparing the integration error with at least one of an upper threshold value or a lower threshold value of one or more of the multiple effective ranges, to determine the effective range in which the integration error is included among the multiple effective ranges.

3. The SOC compensation method of claim 2, wherein said adding the compensation SOC comprises increasing the compensation SOC as the effective range in which the integration error is included is increased, and setting the compensation SOC to “

0”

when the integration error is included within the minimum effective range.

4. The SOC compensation method of claim 2, wherein said adding the compensation SOC comprises subtracting the compensation SOC from the SOC when the integration error exceeds the upper threshold value of another effective range among the multiple effective ranges, which is smaller than the effective range in which the integration error is included and adding the compensation SOC to the SOC when the integration error exceeds the lower threshold value of said another effective range.

5. The SOC compensation method of claim 4, wherein the upper threshold value has a positive value and the lower threshold value has a negative value, and an absolute value of the upper threshold value of the effective range and an absolute value of the lower threshold value of the effective range are the same.

6. The SOC compensation method of claim 1, wherein said calculating the SOC comprises measuring an integration current by employing a current integration method that uses the charge/discharge current of the battery, calculating the SOC corresponding to the integration current, and calculating the SOC voltage by applying the SOC to an open circuit voltage (OCV) table.

7. The SOC compensation method of claim 1, wherein the compensation SOC is calculated according to the following equation:

A=K×

Δ

V₀×

Δ

SOC+ε

where A denotes the compensation SOC, K denotes a constant number, Δ

SOC denotes an SOC set for compensation, ε

denotes an SOC constant number, and Δ

Vo denotes the integration error.

8. A state of charge (SOC) compensation method of a battery management system for compensating an SOC of a battery, the SOC compensation method comprising:

calculating the SOC of the battery and an SOC voltage corresponding to the SOC by using a charge/discharge current of the battery;

measuring a charge/discharge voltage of the battery;

calculating an integration error corresponding to a difference between the SOC voltage and the charge/discharge voltage of the battery;

determining in which effective range the integration error is included among multiple effective ranges; and

adding a compensation SOC to the SOC to generate a compensated SOC, so that the compensated SOC is included within an SOC range corresponding to the effective range.

9. The SOC compensation method of claim 8, wherein said determining in which effective range comprises:

comparing the integration error with at least one of an upper threshold value or a lower threshold value of a minimum effective range among the multiple effective ranges; and

determining the effective range in which the integration error is included by repeating the comparison between the integration error and at least one of an upper threshold value or a lower threshold value of a next smallest effective range among the multiple effective ranges when the integration error exceeds the upper threshold value or the lower threshold value of the minimum effective range among the multiple effective ranges.

10. The SOC compensation method of claim 9, wherein said adding the compensation SOC comprises increasing the compensation SOC as the effective range in which the integration error is included is increased, and setting the compensation SOC to “

0”

when the integration error is included in the minimum effective range.

11. The SOC compensation method of claim 9, wherein said adding the compensation SOC comprises subtracting the compensation SOC from the SOC when the integration error exceeds an upper threshold value of a specific effective range among the multiple effective ranges, and adding the compensation SOC to the SOC when the integration error exceeds a lower threshold value of the specific effective range.

12. The SOC compensation method of claim 10, wherein the upper threshold value has a positive value and the lower threshold value has a negative value, and an absolute value of the upper threshold value and an absolute value of the lower threshold value are the same.

13. The SOC compensation method of claim 8, wherein said calculating the SOC comprises measuring an integration current by employing a current integration method that uses a charge/discharge current of the battery, calculating the SOC corresponding to the integration current, and calculating the SOC voltage by applying the SOC to an open circuit voltage (OCV) table.

14. The SOC compensation method of claim 8, wherein the compensation SOC can be calculated as given in the following equation:

A=K×

Δ

V×

Δ

SOC+ε

where A denotes the compensation SOC, K denotes a constant number, Δ

SOC denotes an SOC set for compensation, ε

denotes an SOC constant number, and Δ

V denotes the integration error.

15. A driving method for driving a battery management system coupled to an engine control unit (ECU) of a vehicle that uses electrical energy, the driving method comprising;

measuring a charge/discharge current and a pack voltage of a battery;

calculating a state of charge (SOC) of the battery and an SOC voltage that corresponds to the SOC by using the charge/discharge current of the battery;

calculating a rheobasic voltage of the battery by using the charge/discharge current of the battery, a voltage of the battery, and an internal resistance of the battery;

calculating an integration error corresponding to a difference between the SOC voltage and the rheobasic voltage;

determining in which effective range the integration error is included among multiple effective ranges; and

adding a compensation SOC corresponding to the effective range in which the integration error is included among the multiple effective ranges to the SOC to make a compensated SOC included in an SOC range that corresponds to a minimum effective range among the multiple effective ranges; and

outputting the compensated SOC as a current SOC of the battery to the ECU.

16. The driving method of claim 15, wherein said determining in which effective range comprises:

comparing the integration error with at least one of an upper threshold value or a lower threshold value of the minimum effective range among the multiple effective ranges; and

determining the effective range in which the integration error is included by repeating the comparison between the integration error and at least one of an upper threshold value or a lower threshold value of a next smallest effective range among the multiple effective ranges when the integration error exceeds the upper threshold value or the lower threshold value of the minimum effective range among the multiple effective ranges.

17. The driving method of claim 16, wherein said adding the compensation SOC comprises increasing the compensation SOC as the effective range in which the integration error is included is increased, and setting the compensation SOC to “

0”

when the integration error is included in the minimum effective range.

18. The driving method of claim 16, wherein said adding the compensation SOC comprises subtracting the compensation SOC from the SOC when the integration error exceeds an upper threshold value of a specific effective range among the multiple effective ranges, and adding the compensation SOC to the SOC when the integration error exceeds a lower threshold value of the specific effective range.

19. The driving method of claim 18, wherein the upper threshold value has a positive value and the lower threshold value has a negative value, and an absolute value of the upper threshold value and an absolute value of the lower threshold value are the same.

20. The driving method of claim 15, wherein said calculating the SOC comprises measuring an integration current by employing a current integration method that uses the charge/discharge current of the battery, calculating the SOC corresponding to the integration current, and calculating the SOC voltage by applying the SOC to an open circuit voltage (OCV) table.

21. The driving method of claim 20, wherein the compensation SOC is calculated according to the following equation:

A=K×

Δ

V₀×

Δ

SOC+ε

where A denotes the compensation SOC, K denotes a constant number, Δ

SOC denotes an SOC set for compensation, ε

denotes an SOC constant number, and Δ

Vo denotes the integration error.

22. A driving method for driving a battery management system coupled to an engine control unit (ECU) of a vehicle that uses electrical energy, the driving method comprising;

measuring a charge/discharge current and a pack voltage of a battery;

calculating a state of charge (SOC) of the battery and an SOC voltage that corresponds to the SOC by using the charge/discharge current of the battery;

measuring a charge/discharge voltage of the battery;

calculating an integration error that corresponds to a difference between the SOC voltage and the charge/discharge voltage;

determining in which effective range the integration error is included among multiple effective ranges;

adding a compensation SOC corresponding to the effective range in which the integration error is included among the multiple effect ranges to the SOC to make a compensated SOC included in an SOC range that corresponds to a minimum effective range among the multiple effective ranges; and

outputting the compensated SOC as a current SOC of the battery to the ECU.

23. The driving method of claim 22, wherein said determining in which effective range comprises:

comparing the integration error with at least one of an upper threshold value or a lower threshold value of the minimum effective range among the multiple effective ranges; and

determining the effective range in which the integration error is included by repeating the comparison between the integration error and at least one of an upper threshold value or a lower threshold value of a next smallest effective range among the multiple effective ranges when the integration error exceeds the upper threshold value or the lower threshold value of the minimum effective range among the multiple effective ranges.

24. The driving method of claim 23, wherein said adding the compensation SOC comprises increasing the compensation SOC as the effective range in which the integration error is included is increased, and setting the compensation SOC to “

0”

when the integration error is included in the minimum effective range.

25. The driving method of claim 23, wherein said adding the compensation SOC comprises subtracting the compensation SOC from the SOC when the integration error exceeds an upper threshold value of a specific effective range among the multiple effective ranges, and adding the compensation SOC to the SOC when the integration error exceeds a lower threshold value of the specific effective range.

26. The driving method of claim 25, wherein the upper threshold value has a positive value and the lower threshold value has a negative value, and an absolute value of the upper threshold value and an absolute value of the lower threshold value are the same.

27. The driving method of claim 22, wherein said calculating the SOC comprises measuring an integration current by employing a current integration method that uses the charge/discharge current of the battery, calculating the SOC corresponding to the integration current, and calculating the SOC voltage by applying the SOC to an open circuit voltage (OCV) table.

28. The driving method of claim 22, wherein the compensation SOC is calculated according to the following equation:

A=K×

Δ

V×

Δ

SOC+ε

where A denotes the compensation SOC, K denotes a constant number, Δ

SOC denotes an SOC set for compensation, ε

denotes an SOC constant number, and Δ

V denotes the integration error.

29. A battery management system for managing a battery, the battery management system being adapted to output a state of charge (SOC) of the battery to an engine control unit (ECU) of a vehicle that uses electrical energy, the battery management system comprising:

an integration SOC calculator for calculating the SOC by using a charge/discharge current of the battery;

an integration voltage calculator for calculating an integration voltage that corresponds to the SOC;

a rheobasic voltage calculator for calculating a rheobasic voltage of the battery by using a pack voltage of the battery, the charge/discharge current of the battery, and an internal resistance of the battery;

an effective range determiner for calculating an integration error by using the integration voltage and the rheobasic voltage, determining in which effective range the integration error is included among multiple effective ranges, and outputting a specific effective range excess signal or a specific effective range below signal according to a result of the determination;

an SOC compensator for compensating the integration error to be included within a minimum effective range among the multiple effective ranges by adding a compensation SOC to the SOC when the output of the effective range determiner indicates that the integration error is not included in the specific effective range, the compensation SOC being set in accordance with the output of the effective range determiner; and

an SOC output unit for outputting an output of the SOC compensator as a current SOC of the battery to the ECU.

30. The battery management system of claim 29, wherein the effective range determiner is adapted to compare the integration error and at least one of an upper threshold value or a lower threshold value of the minimum effective range among the multiple effective ranges, and to determine in which effective range the integration error is included by repeating the comparison between the integration error and at least one of an upper threshold value or a lower threshold value of a next smallest effective range among the multiple effective ranges when the integration error exceeds the upper threshold value or the lower threshold value of the minimum effective range among the multiple effective ranges.

31. The battery management system of claim 30, wherein the effective range determiner is adapted to increase the compensation SOC as the effective range in which the integration error is included is increased, and sets the compensation SOC to “

0”

when the integration error is included in the minimum effective range.

32. The battery management system of claim 31, wherein the upper threshold value has a positive value and the lower threshold value has a negative value, and an absolute value of the upper threshold value and an absolute value of the lower threshold value are the same.

33. The battery management system of claim 32, wherein the SOC compensator is adapted to subtract the compensation SOC from the SOC when the integration error exceeds an upper threshold value of the specific effective range and to add the compensation SOC to the SOC when the integration error exceeds a lower threshold value of the specific effective range.

34. The battery management system of claim 33, wherein the integration voltage calculator is adapted to calculate an integration voltage that corresponds to the SOC by applying the SOC to an SOC to open circuit voltage (OCV) table.

35. The battery management system of claim 29, wherein the compensation SOC can be calculated as given in the following equation:

A=K×

Δ

V₀×

Δ

SOC+ε

where A denotes the compensation SOC, K denotes a constant number, Δ

SOC denotes an SOC set for compensation, ε

denotes an SOC constant number, and Δ

Vo denotes the integration error.

41. The battery management system of claim 33, wherein the integration voltage calculator is adapted to calculate an integration voltage that corresponds to the SOC by applying the SOC to an SOC to open circuit voltage (OCV) table.

42. The battery management system of claim 29, wherein the compensation SOC can be calculated as given in the following equation:

A=K×

Δ

V×

Δ

SOC+ε

where A denotes the compensation SOC, K denotes a constant number, Δ

SOC denotes an SOC set for compensation, ε

denotes an SOC constant number, and Δ

V denotes the integration error.

36. A battery management system for managing a battery, the battery management system being adapted to output a state of charge (SOC) of the battery to an engine control unit (ECU) of a vehicle that uses electrical energy, the battery management system comprising:

an integration SOC calculator for calculating the SOC by using a charge/discharge current of the battery;

an integration voltage calculator for calculating an integration voltage that corresponds to the SOC;

an effective range determiner for calculating an integration error by using the integration voltage and a charge/discharge voltage of the battery, determining in which effective range the integration error is included among multiple effective ranges, and outputting a specific effective range excess signal or a specific effective range below signal according to a result of the determination;

an SOC compensator for compensating the integration error to be included within a minimum effective range among the multiple effective ranges by adding a compensation SOC to the SOC when the output of the effective range determiner indicates that the integration error is not included in the specific effective range, the compensation SOC being set in accordance with an output of the effective range determiner; and

an SOC output unit for outputting an output of the SOC compensator as a current SOC of the battery to the ECU.

37. The battery management system of claim 36, wherein the effective range determiner is adapted to compare the integration error and at least one of an upper threshold value or a lower threshold value of the minimum effective range among the multiple effective ranges, and to determine in which effective range the integration error is included by repeating the comparison between the integration error and at least one of an upper threshold value or a lower threshold value of a next smallest effective range among the multiple effective ranges when the integration error exceeds the upper threshold value or the lower threshold value of the minimum effective range among the multiple effective ranges.

38. The battery management system of claim 37, wherein the effective range determiner is adapted to increase the compensation SOC as the effective range in which the integration error is included is increased, and to set the compensation SOC to “

0”

when the integration error is included in the minimum effective range.

39. The battery management system of claim 38, wherein the upper threshold value has a positive value and the lower threshold value has a negative value, and an absolute value of the upper threshold value and an absolute value of the lower threshold value are the same.

40. The battery management system of claim 39, wherein the SOC compensator is adapted to subtract the compensation SOC from the SOC when the integration error exceeds an upper threshold value of the specific effective range and to add the compensation SOC to the SOC when the integration error exceeds a lower threshold value of the specific effective range.