Apparatus and method for estimating SOC of secondary battery including blended cathode material

Patent metadata

Field	Value
Publication number	US-9720045-B2
Application number	US-201414565647-A
Country	US
Kind code	B2
Filing date	Dec 10, 2014
Priority date	Jun 13, 2012
Publication date	Aug 1, 2017
Grant date	Aug 1, 2017

Abstract

Disclosed is an apparatus and method for estimating a SOC of a secondary battery containing a blended cathode material. The SOC estimating apparatus estimates a SOC of a secondary battery including a cathode having a blended cathode material containing a first cathode material and a second cathode material with different operating voltage ranges, an anode having an anode material, and a separator for separating the cathode from the anode, and the apparatus includes a sensor configured to measure a discharge inception voltage and a final discharge voltage when the secondary battery is discharged for a predetermined time, and a control unit configured to estimate SOC of the secondary battery corresponding to the measured discharge inception voltage and the measured final discharge voltage by using a predetermined relationship between the discharge inception voltage and the final discharge voltage and the SOC of the secondary battery.

First claim

What is claimed is:

1. An apparatus for estimating a state of charge (SOC) of a secondary battery, which includes a cathode having a blended cathode material containing a first cathode material and a second cathode material with different operating voltage ranges, an anode having an anode material, and a separator for separating the cathode from the anode, the apparatus comprising:
a sensor configured to measure a discharge inception voltage and a final discharge voltage when the secondary battery is discharged for a predetermined time; and
a control unit configured to estimate a SOC of the secondary battery corresponding to the measured discharge inception voltage and the measured final discharge voltage by using a predetermined relationship between the discharge inception voltage and the final discharge voltage and the SOC of the secondary battery,
wherein the discharge inception voltage is a key-on voltage measured right after the secondary battery in a no-load state comes to a key-on state, and
wherein the final discharge voltage is a key-on discharge voltage measured after the secondary battery in the key-on state performs key-on discharge for a predetermined time.

2. The apparatus for estimating a SOC of a secondary battery according to claim 1 ,
wherein the predetermined relationship is a look-up table which defines a relationship between the key-on voltage and the key-on discharge voltage and the SOC of the secondary battery.

3. The apparatus for estimating a SOC of a secondary battery according to claim 2 , further comprising a storage unit in which the look-up table is stored.

4. The apparatus for estimating a SOC of a secondary battery according to claim 1 ,
wherein the predetermined relationship is a look-up function using the key-on voltage and the key-on discharge voltage as input parameters and the SOC as an output parameter.

5. The apparatus for estimating a SOC of a secondary battery according to claim 4 , further comprising a storage unit in which the look-up function is stored.

6. The apparatus for estimating a SOC of a secondary battery according to claim 1 ,
wherein the relationship is predetermined by applying the same discharge condition as the key-on discharge.

7. The apparatus for estimating a SOC of a secondary battery according to claim 1 ,
wherein the key-on discharge is a constant current discharge.

8. The apparatus for estimating a SOC of a secondary battery according to claim 1 , further comprising a discharge unit selectively connected to the secondary battery,
wherein the control unit connects the discharge unit to the secondary battery in order to discharge the secondary battery for a predetermined time.

9. The apparatus for estimating a SOC of a secondary battery according to claim 1 ,
wherein the key-on discharge is automatically performed when the secondary battery comes to a key-on state.

10. The apparatus for estimating a SOC of a secondary battery according to claim 1 ,
wherein when the secondary battery is in a no-load state, the SOC falls within a SOC range which causes a voltage relaxation phenomenon by transferring operating ions between the first cathode material and the second cathode material.

11. The apparatus for estimating a SOC of a secondary battery according to claim 10 ,
wherein when the secondary battery is in a no-load state, the voltage of the secondary battery changes to follow a voltage relaxation profile originating from the voltage relaxation phenomenon.

12. The apparatus for estimating a SOC of a secondary battery according to claim 11 ,
wherein the key-on discharge voltage is a voltage selected from a voltage change pattern which appears while a voltage of the secondary battery is dropped and then returns to the voltage relaxation profile during the key-on discharge.

13. The apparatus for estimating a SOC of a secondary battery according to claim 12 , wherein the key-on discharge voltage is a voltage measured when the key-on discharge is completed, a voltage measured when a predetermined time passes after the key-on discharge starts, a voltage measured when a predetermined time passes after the key-on discharge is completed, a voltage measured when the voltage of the secondary battery returns to the voltage relaxation profile, a voltage measured when a minimum point is formed in a voltage change pattern of the secondary battery formed by the key-on discharge, or a voltage measured when the change of voltage per unit time is greatest in the voltage change pattern of the secondary battery formed by the key-on discharge.

14. The apparatus for estimating a SOC of a secondary battery according to claim 1 , further comprising a display unit for displaying the estimated SOC as a graphic interface,
wherein the control unit is configured to output the estimated SOC to the display unit.

15. The apparatus for estimating a SOC of a secondary battery according to claim 1 , further comprising a storage unit in which the estimated SOC is stored,
wherein the control unit is configured to store the estimated SOC in the storage unit.

16. The apparatus for estimating a SOC of a secondary battery according to claim 1 ,
wherein the control unit is configured to output the estimated SOC to the outside.

17. An apparatus for estimating a SOC of a secondary battery, which includes a cathode having a blended cathode material containing a first cathode material and a second cathode material with different operating voltage ranges, an anode having an anode material, and a separator for separating the cathode from the anode, the apparatus comprising:
a sensor configured to measure a discharge inception voltage and a final discharge voltage when the secondary battery is discharged for a predetermined time before the voltage of the secondary battery in a no-load state reaches an equilibrium state voltage; and
a control unit configured to estimate a SOC of the secondary battery corresponding to the measured discharge inception voltage and the measured final discharge voltage by using a predetermined relationship between the discharge inception voltage and the final discharge voltage and the SOC of the secondary battery.

18. An apparatus for estimating a SOC of a secondary battery, comprising:
a sensor configured to measure a discharge inception voltage and a final discharge voltage of the secondary battery when the secondary battery is discharged for a predetermined time before the voltage of the secondary battery in a no-load state reaches an equilibrium state voltage; and
a control unit configured to estimate a SOC of the secondary battery corresponding to the measured discharge inception voltage and the measured final discharge voltage by using a predetermined relationship between the discharge inception voltage and the final discharge voltage and the SOC of the secondary battery.

19. A method for estimating a SOC of a secondary battery, which includes a cathode having a blended cathode material containing a first cathode material and a second cathode material with different operating voltage ranges, an anode having an anode material, and a separator for separating the cathode from the anode, the method comprising:
measuring a discharge inception voltage and a final discharge voltage when the secondary battery is discharged for a predetermined time; and
estimating a SOC of the secondary battery corresponding to the measured discharge inception voltage and the measured final discharge voltage by using a predetermined relationship between the discharge inception voltage and the

Assignees

• Lg Chemical Ltd

Inventors

• Joe Won-Tae
• Cha Sun-Young
• Chung Geun-Chang

Classifications

• H01M2004/028

  Positive electrodes · CPC title

• G01R31/367

  Software therefor, e.g. for battery testing using modelling or look-up tables · CPC title

• H01M4/364

  as mixtures · CPC title

• G01R31/3648

  comprising digital calculation means, e.g. for performing an algorithm · CPC title

• G01R31/382 Primary

  Arrangements for monitoring battery or accumulator variables, e.g. SoC · CPC title