Apparatus and method for controlling step charging of secondary battery

Patent metadata

Field	Value
Publication number	US-11876397-B2
Application number	US-201917280789-A
Country	US
Kind code	B2
Filing date	Oct 30, 2019
Priority date	Dec 21, 2018
Publication date	Jan 16, 2024
Grant date	Jan 16, 2024

Abstract

Disclosed is an apparatus and method for controlling step charging of a secondary battery. A charging control unit determines a SOC, an OCV and a polarization voltage of the secondary battery, determines an OCV deviation corresponding to a difference between the OCV and a predefined minimum OCV value, determines a correction factor corresponding to the polarization voltage and the OCV deviation, determines a look-up SOC by correcting the SOC according to the correction factor, determines the magnitude of a charging current corresponding to the look-up SOC, and provides the determined charging current to a charging device.

First claim

What is claimed is:

1. An apparatus for controlling step charging of a secondary battery, comprising:
a voltage measuring unit including a voltage sensor, a current measuring unit including a current sensor, and a temperature measuring unit including a temperature sensor configured to respectively measure a voltage, a current and a temperature of the secondary battery; and
a charging control unit including a processor and operably coupled to the voltage measuring unit, the current measuring unit and the temperature measuring unit,
wherein the charging control unit is configured to execute control logics including:
a control logic to estimate a state of charge (SOC) and an open circuit voltage (OCV) of the secondary battery based on the measured voltage value, the measured current value, and the measured temperature value before the start of charging of the secondary battery;
a control logic to determine a polarization voltage of the secondary battery from an internal resistance of the secondary battery, the measured current value, and the estimated OCV;
a control logic to determine an OCV deviation corresponding to a difference between the estimated OCV and a predefined minimum OCV value;
a control logic to determine a correction factor corresponding to the determined polarization voltage and the determined OCV deviation with reference to a predefined correlation between the polarization voltage and the correction factor and between the OCV deviation and the correction factor;
a control logic to determine a look-up SOC by correcting the estimated SOC according to the correction factor;
a control logic to determine a magnitude of a charging current corresponding to the look-up SOC and the measured temperature value with reference to a predefined correlation between the SOC and the charging current and between the temperature and the charging current; and
a control logic to provide the determined charging current to a charging device so that a charging current corresponding to the determined magnitude of the charging current is applied to the secondary battery.

2. The apparatus for controlling step charging of the secondary battery according to claim 1 ,
wherein the charging control unit is configured to periodically estimate the SOC of the secondary battery from the measured voltage value, the measured current value, and the measured temperature value by using an extended Kalman filter while the secondary battery is in a discharging mode or a sleeping mode and to determine the look-up SOC by correcting an SOC estimated just before the start of charging among the plurality of estimated SOCs.

3. The apparatus for controlling step charging of the secondary battery according to claim 2 ,
wherein the charging control unit is configured to estimate an OCV corresponding to the estimated SOC with reference to a predefined correlation between the SOC and the OCV.

4. The apparatus for controlling step charging of the secondary battery according to claim 1 ,
wherein the charging control unit is configured to determine the polarization voltage according to an equation below:
dV pol [k]=V cell [k]−V OCV [k]−I[k]R 0

where k is a time index, dV pol [k] is a polarization voltage, V cell [k] is a voltage estimated by an extended Kalman filter or a measured voltage, V OCV [k] is an OCV, R 0 is an internal resistance of the secondary battery, and I[k] is a charging current of the secondary battery.

5. The apparatus for controlling step charging of the secondary battery according to claim 1 ,
wherein the charging control unit is configured to determine the OCV deviation according to an equation below:
dV OCV [k]=V OCV [k]−V OCV,min [k]

where k is a time index, dV ocv [k] is an OCV deviation, V ocv [k] is an OCV, and V ocv,min is a predefined minimum OCV value.

6. The apparatus for controlling step charging of the secondary battery according to claim 1 ,
wherein the charging control unit is configured to determine the look-up SOC according to an equation below:
SOC lookup [k ]=SOC estimated [k]−d SOC( dV OCV [k],dV pol [k ])

where k is a time index, SOC lookup [k] is a look-up SOC, SOC estimate [k] is an estimated SOC, dV ocv [k] is an OCV deviation, dV pol [k] is a polarization voltage, and dSOC is a look-up table defining a correlation between the OCV deviation and the correction factor and between the polarization voltage and the correction factor.

7. The apparatus for controlling step charging of the secondary battery according to claim 6 ,
wherein the charging control unit is configured to determine the correction factor to be proportional to the OCV deviation and to determine the correction factor to be inversely proportional to the polarization voltage.

8. An electric-driven device, comprising the apparatus for controlling step charging of the secondary battery according to claim 1 .

9. A method for controlling step charging of a secondary battery, comprising:
(a) measuring a voltage, a current and a temperature of the secondary battery while the secondary battery is in a discharging mode or a sleeping mode;
(b) estimating a state of charge (SOC) and an open circuit voltage (OCV) of the secondary battery based on the measured voltage value, the measured current value, and the measured temperature value before the start of charging of the secondary battery;
(c) determining a polarization voltage of the secondary battery from an internal resistance of the secondary battery, the measured current value, and the estimated OCV;
(d) determining an OCV deviation corresponding to a difference between the estimated OCV and a predefined minimum OCV value;
(e) determining a correction factor corresponding to the determined polarization voltage and the determined OCV deviation with reference to a predefined correlation between the polarization voltage and the correction factor and between the OCV deviation and the correction factor;
(f) determining a look-up SOC by correcting the estimated SOC according to the correction factor;
(g) determining a magnitude of a charging current corresponding to the look-up SOC and the measured temperature value with reference to a predefined correlation between the SOC and the magnitude of the charging current and between the temperature the magnitude of the charging current; and
(h) providing the determined charging current to a charging device so that a charging current corresponding to the determined magnitude of the charging current is applied to the secondary battery.

10. The method for controlling step charging of the secondary battery according to claim 9 ,
wherein in the (b) step, the SOC of the secondary battery is periodically estimated from the measured voltage value, the measured current value, and the measured temperature value by using an extended Kalman filter while the secondary battery is in the discharging mode or the sleeping mode, and
in the (f) step, the look-up SOC is determined by correcting an SOC estimated just before the start of charging among the plurality of estimated SOCs.

11. The method for controlling step charging of the secondary battery according to claim 10 ,
wherein in the (b) step, an OCV corresponding to the estimated SOC is estimated with reference to a predefined correlation between the SOC and the OCV.

12. The method for controlling step charging of the secondary battery according to claim 9 ,
wherein in the (c) step, the polarization voltage is determined according to an equation below:
dV pol [k]=V cell [k]−V OCV [k]−I[k]R 0

where k is a time index, dV pol [k] is a polarization voltage, V cell [k] is

Assignees

• Lg Chemical Ltd
• Lg Energy Solution Ltd

Inventors

• Lim Jin-Hyung
• Kim Young-Jin
• Nam Gi-Min
• Ahn Hyoung Jun
• Lee Kyu-Chul
• Joe Won-Tae

Classifications

• H02J7/977

  of the battery · CPC title

• H02J7/965 Primary

  obtained with the battery disconnected from the charge or discharge circuit · CPC title

• H02J7/96

  in response to battery voltage · CPC title

• H02J7/94 Primary

  in response to battery current · CPC title

• H02J7/80

  including monitoring or indicating arrangements · CPC title