Method for determining resistance factor of secondary battery, and apparatus and method for estimating charge power using determined resistance factor

Patent metadata

Field	Value
Publication number	US-10670664-B2
Application number	US-201615317888-A
Country	US
Kind code	B2
Filing date	Feb 2, 2016
Priority date	Feb 2, 2015
Publication date	Jun 2, 2020
Grant date	Jun 2, 2020

Abstract

A resistance factor determining method of a secondary battery according to the present disclosure determines, when the secondary battery has a certain temperature and state of charge, a primary differential value regarding a charge initial I-V profile calculated from a current value at a point of intersection at which a charge final I-V profile according to changes in magnitude of the charging current meets a boundary line set to a charge upper limit as the resistance factor corresponding to the temperature and state of charge. Further, a charge power estimating apparatus and method according to the present disclosure estimates a charge power corresponding to the temperature and state of charge of the secondary battery while the secondary battery is being charged using the resistance factor pre-defined according to the state of charge and temperature of the secondary battery.

First claim

What is claimed is:

1. A resistance factor determining method of a secondary battery, the method comprising:
(a) measuring charge initial voltage data and charge final voltage data according to changes in magnitude of a charging current per temperature and state of charge of the secondary battery, and storing the charge initial voltage data and the charge final voltage data in a memory;
(b) determining a charge final current-voltage (I-V) profile from the final voltage data, and determining a point of intersection at which the charge final I-V profile meets a boundary line corresponding to a charge upper limit current or a charge upper limit voltage pre-set to a charge upper limit condition;
(c) determining a charge initial I-V profile from charge initial voltage data, and determining a primary differential value regarding the charge initial I-V profile calculated based on a current value of the point of intersection; and
(d) designating the determined primary differential value as a resistance factor corresponding to a temperature and state of charge of the secondary battery,
wherein the charge initial voltage data is voltage data measured at a time point within 1 second after the charging current was applied to the secondary battery, and
wherein the charge final voltage data is voltage data measured at a time point when applying of the charging current to the secondary battery ended.

2. The method of claim 1 , further comprising defining a resistance factor look-up table in the memory such that the resistance factor of the secondary battery may be mapped by the temperature and state of charge of the secondary battery; and
storing the determined resistance factor in the defined resistance factor look-up table.

3. The method of claim 1 , wherein step (a) comprises:
maintaining the temperature of the secondary battery constant;
proceeding a charge test of applying a plurality of charging currents having different magnitudes to the secondary battery per state of charge of the secondary battery; and
measuring and storing the charge initial voltage and the charge final voltage of the secondary battery every time each charging current is applied.

4. The method of claim 3 , wherein the charge test is paused when a magnitude of the charging current applied to the secondary battery is greater than the charge upper limit current or when a latest measured charge final voltage of the secondary battery is greater than the charge upper limit voltage.

5. A charge power estimating apparatus of a secondary battery comprising:
a storage unit where a resistance factor look-up table for referencing a resistance factor by a temperature and state of charge of the secondary battery is pre-stored, wherein the resistance factor is determined by the method of claim 1 ;
a sensor unit that measures a charging current and temperature of the secondary battery while the secondary battery is being charged; and
a control unit that determines the state of charge of the secondary battery, determines the resistance factor corresponding to the determined state of charge and the measured temperature with reference to the resistance factor look-up table, and estimates the charge power of the secondary battery from the determined resistance factor and the measured charging current,
wherein, when the secondary battery has a certain temperature and state of charge, the resistance factor is a primary differential value regarding a charge initial I-V profile calculated from a current value of a point of intersection at which a charge final I-V profile according to changes in magnitude of the charging current meets a boundary line set to a charge upper limit.

6. The apparatus of claim 5 , wherein the boundary line is a boundary line that indicates a charge upper limit current and a charge upper limit voltage.

7. The apparatus of claim 5 , wherein the charge initial I-V profile is a graph that defines a correlation between the charging current applied to the secondary battery and a voltage measured right after the corresponding charging current is applied when a plurality of charging currents having different magnitudes are applied to the secondary battery.

8. The apparatus of claim 7 , wherein voltage data constructing the charge initial I-V profile is voltage data measured within 1 second after each charging current was applied to the secondary battery.

9. The apparatus of claim 5 , wherein the charge final I-V profile is a graph that defines a correlation between the charging current applied to the secondary battery and a voltage measured at a time point when the applying of the corresponding charging current ended when a plurality of charging currents having different magnitudes are applied to the secondary battery.

10. The apparatus of claim 5 , wherein the control unit is configured to store the estimated charge power in the storage unit.

11. The apparatus of claim 5 , further comprising a display unit connected with the control unit, wherein the control unit displays the estimated charge power through the display unit.

12. The apparatus of claim 5 , further comprising a communication interface connected with the control unit,
wherein the control unit externally transmits the estimated charge power through the communication interface.

13. A charge power estimating method of a secondary battery, the method comprising:
providing a resistance factor look-up table for referencing a resistance factor by a temperature and state of charge of the secondary battery, wherein the resistance factor is determined by the method of claim 1 ;
measuring a charging current and the temperature of the secondary battery while the secondary battery is being charged;
determining the state of charge of the secondary battery;
determining the resistance factor corresponding to the deteiinined state of charge and the measured temperature with reference to the resistance factor look-up table; and
estimating a charge power of the secondary battery from the determined resistance factor and the measured charging current;
wherein, when the secondary battery has a certain temperature and state of charge, the resistance factor is a primary differential value regarding a charge initial profile calculated from a current value at a point of intersection at which a charge final I-V profile according to changes in magnitude of the charging current meets a boundary line set to a charge upper limit.

14. The method of claim 13 , wherein the boundary line is a boundary line that indicates a charge upper limit current and a charge upper limit voltage.

15. The method of claim 13 , wherein the charge initial I-V profile is a graph that defines a correlation between the charging current applied to the secondary battery and a voltage measured right after the corresponding charging current was applied when a plurality of charging currents having different magnitudes are applied to the secondary battery.

16. The method of claim 15 , wherein voltage data constructing the charge initial I-V profile is voltage data measured within 1 second after each charging current was applied to the secondary battery.

17. The method of claim 13 , wherein the charge final I-V profile is a graph that defines a correlation between the charging current applied to the secondary battery and a voltage measured at a time point when the applying of the corresponding charging current ended when a plurality of charging currents having different magnitudes are applied to the secondary battery.

18. The method of claim 13 , further comprising storing, d

Assignees

• Lg Chemical Ltd

Inventors

• Cha Sun-Young
• Joe Won-Tae

Classifications

• G01R31/367

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

• G01R31/3648

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

• G01R27/02

  Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant (by measuring phase angle only G01R25/00) · CPC title

• G01R31/389 Primary

  Measuring internal impedance, internal conductance or related variables · CPC title

• G08C19/02

  in which the signal transmitted is magnitude of current or voltage (G08C19/36, G08C19/38 take precedence) · CPC title