Battery management system and method of estimating battery state of charge

• US 20120091946A1
• Filed: 09/22/2011
• Published: 04/19/2012
• Est. Priority Date: 10/13/2010
• Status: Active Grant

• Current Assignee: Samsung SDI Company Limited
• Original Assignee: Samsung SDI Company Limited
• Inventors: Miyazawa, Hiroshi, Murakami, Yusai
• Granted Patent: US 8,963,506 B2
• Time in Patent Office: Days
• US Class Current: 320/107
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/3828 using current integration
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements

Abstract

A battery management system and method accurately estimate a state of charge (SOC) of a battery. For this, the battery management system may include a unit SOC calculator calculating a unit SOC by using a charge/discharge current of a battery, an electromotive force SOC calculator calculating an electromotive force SOC using an electromotive force of the battery; a corrector calculating a compensation amount using the electromotive force SOC and a previous SOC, and an SOC calculator calculating a current SOC using the unit SOC, the previous SOC, and the compensation amount.

Claims

1. A battery management system, comprising:

a unit SOC calculator calculating a unit SOC using a charge/discharge current of a battery;

an electromotive force SOC calculator calculating an electromotive force SOC using an electromotive force of the battery;

a corrector calculating a compensation amount using the electromotive force SOC and a previous SOC; and

an SOC calculator calculating a current SOC by adding the unit SOC, the previous SOC, and the compensation amount.

2. The battery management system as claimed in claim 1, wherein:

the SOC calculator calculates the current SOC by

SOCn+1=SOCn+SOCi+Kp(SOCv−

SOCn)+Ki∫

(SOCv−

SOCn)dt

(here, SOCn+1 is the current SOC, SOCn is the previous SOC, SOCi is the unit SOC, SOCv is the electromotive force SOC, and Kp and Ki are constants).

3. The battery management system as claimed in claim 1, further comprising:

a sensing unit sensing the charge/discharge current and battery terminal voltage from the battery and measuring an internal resistance of the battery by using the charge/discharge current and the battery terminal voltage.

4. The battery management system as claimed in claim 3, wherein:

the electromotive force SOC calculator determines a polarization voltage using the charge/discharge current and the internal resistance, and calculates the electromotive force by subtracting the polarization voltage from the battery terminal voltage.

5. A battery management system, comprising:

a unit SOC calculator calculating a unit SOC by using a charge/discharge current of a battery;

an electromotive force SOC calculator calculating an electromotive force SOC using an electromotive force of the battery;

an integration SOC calculator calculating an integration SOC by adding the unit SOC and a previous SOC;

a corrector calculating a compensation amount by using the integration SOC, the electromotive force SOC, and the previous SOC; and

an SOC calculator calculating a current SOC by adding the integration SOC and the compensation amount.

6. The battery management system as claimed in claim 5, wherein:

the SOC calculator calculates the current SOC by

SOCn+1=SOCI+SOCi+Kp(SOCv−

SOCI)+Ki∫

(SOCv−

SOCI)dt

(here, SOCn+1 is the current SOC, SOCI is the integration SOC, SOCv is the electromotive force SOC, and Kp and Ki are constants).

7. The battery management system as claimed in claim 6, wherein:

the unit SOC calculator integrates the charge/discharge current during a unit time to calculate a unit time charge/discharge charge amount, and divides the unit time charge/discharge charge amount by the total charge/discharge charge amount of the battery to calculate the unit SOC.

8. The battery management system as claimed in claim 7, further comprising:

a correction unit correcting the compensation amount according to the unit time charge/discharge charge amount; and

the SOC calculator calculates the current SOC by adding the corrected compensation amount and the integration SOC.

9. The battery management system as claimed in claim 8, wherein:

the correction unit corrects the compensation amount for the current SOC to be included in a predetermined SOC range with reference to the previous SOC when the unit time charge/discharge charge amount is smaller than a predetermined threshold unit charge/discharge charge amount.

10. The battery management system as claimed in claim 8, wherein:

the correction unit corrects the compensation amount for the current SOC to be increased or decreased corresponding to the charge/discharge of the battery.

11. The battery management system as claimed in claim 5, further comprising:

a sensing unit sensing the charge/discharge current and battery terminal voltage from the battery and measuring an internal resistance of the battery by using the charge/discharge current and the battery terminal voltage.

12. The battery management system as claimed in claim 5, wherein:

the electromotive force SOC calculator determines a polarization voltage by using the charge/discharge current and the internal resistance, and calculates the electromotive force by subtracting the polarization voltage from the battery terminal voltage.

13. A method for estimating a battery SOC using a battery management system, comprising:

calculating a unit SOC by using a charge/discharge current of a battery;

calculating an electromotive force SOC by using an electromotive force of the battery;

calculating a compensation amount by using the electromotive force SOC and the previous SOC; and

calculating a current SOC by adding the unit SOC, the previous SOC, and the compensation amount.

14. The method as claimed in claim 13, wherein:

the calculation of the current SOC is executed by

SOCn+1=SOCn+SOCi+Kp(SOCv−

SOCn)+Ki∫

(SOCv−

SOCn)dt

(here, SOCn+1 is the current SOC, SOCn is the previous SOC, SOCi is the unit SOC, SOCv is the electromotive force SOC, and Kp and Ki are constants).

15. A method for estimating a battery SOC using a battery management system, comprising:

calculating a unit SOC by using a charge/discharge current of a battery;

calculating an electromotive force SOC by using an electromotive force of the battery;

calculating an integration SOC by adding the unit SOC and the previous SOC;

calculating a compensation amount by using the integration SOC, the electromotive force SOC, and the previous SOC; and

calculating a current SOC by adding the integration SOC and the compensation amount.

16. The method as claimed in claim 15, wherein:

calculating the current SOC is executed by

SOCn+1=SOCI+SOCi+Kp(SOCv−

SOCI)+Ki∫

(SOCv−

SOCI)dt

(here, SOCn+1 is the current SOC, SOCI is the integration SOC, SOCv is the electromotive force SOC, and Kp and Ki are constants).

17. The method as claimed in claim 15, wherein calculating the unit SOC includes:

integrating the charge/discharge current during a unit time to calculate a unit time charge/discharge charge amount; and

dividing the unit time charge/discharge charge amount by the total charge/discharge charge amount of the battery.

18. The method as claimed in claim 17, further comprising correcting the compensation amount according to the unit time charge/discharge charge amount.

19. The method as claimed in claim 18, wherein correcting the compensation amount is executed for the current SOC to be included in a predetermined SOC range with reference to the previous SOC when the unit time charge/discharge charge amount is smaller than a predetermined threshold unit charge/discharge charge amount.

20. The method as claimed in claim 18, wherein correcting the compensation amount is executed for the current SOC to be increased or decreased corresponding to the charge/discharge of the battery, respectively.