System and method for managing battery on the basis of time required for charging

Patent metadata

Field	Value
Publication number	US-2018031642-A1
Application number	US-201615372836-A
Country	US
Kind code	A1
Filing date	Dec 8, 2016
Priority date	Aug 1, 2016
Publication date	Feb 1, 2018
Grant date	—

Abstract

Provided are a weighted least square (WLS)-based state of health (SOH) estimating system and method. A battery management system according to an aspect of the present invention includes a measurer measuring a time required for charging at each of preset voltage intervals within a preset voltage range in which a battery is charged with a constant current; and an estimator estimating a parameter using an estimated value of time required for charging according to a preset metamodel and a measured value of a time required for charging after completion of the constant current charging.

First claim

What is claimed is:

1 . A state of health (SOH) estimating system comprising:
a measurer determining a measured value of a time required for charging at each of preset voltage intervals within a preset voltage range in which a battery is charged with a constant current; and a parameter estimator determining an estimated value of a time required for charging at each of the voltage intervals by a preset metamodel when a battery voltage is higher than the voltage range, and estimating a battery SOH in which an error between the measured value and the estimated value based on a weighted least square (WLS) is the lowest.

2 . The SOH estimating system according to claim 1 , wherein the preset voltage range is 3600 mV to 4040 mV, and the voltage interval is 20 mV.

3 . The SOH estimating system according to claim 1 , wherein the measurer selects cells having the minimum, average, and maximum voltages, among all the cells forming the battery, and measures a time required for charging at each of the voltage intervals of the three selected cells.

4 . The SOH estimating system according to claim 3 , wherein the parameter estimator estimates the battery SOH of each of the three selected cells, and determines an SOH of the cell having the maximum voltage, as the battery SOH.

5 . The SOH estimating system according to claim 1 , further comprising:
an initializer determining an initial time of a time required for charging by converting a result obtained by dividing a residual capacity by a charge current into a unit of second, before the constant current charging.

6 . The SOH estimating system according to claim 5 , wherein when a parameter is initially estimated after the battery starts to be charged, the parameter estimator determines an estimated value of a time required for charging by changing a charge curve when an SOH is 1 to correspond to the initial time.

7 . The SOH estimating system according to claim 5 , wherein the charge current is a value measured by a current sensor.

8 . The SOH estimating system according to claim 1 , wherein the parameter estimator updates a predicted SOH, determines an estimate value of a time required for charging at each of the voltage intervals corresponding to the predicted SOH by the metamodel, determines a residual vector by subtracting a measured value of each of the voltage intervals from the determined estimated value of each of the voltage intervals, and estimates the predicted SOH in which a weighted least square sum of the residual vector is minimized, as the battery SOH.

9 . The SOH estimating system according to claim 8 , wherein when the residual vector is first determined after the battery starts to be charged, the predicted SOH is set to 1, and sequentially reduced according to a number of updating the predicted SOH within a preset unit by the metamodel.

10 . The SOH estimating system according to claim 8 , wherein the parameter estimator estimates the battery SOH, while updating the predicted SOH within a preset maximum repetition number and while updating the predicted SOH until the weighted least square sum of the residual vector is converged.

11 . The SOH estimating system according to claim 8 , wherein the weight value is set to be in inverse proportion to an error variance of the residual vector, a difference between the estimated value of a time required for charging at each of the voltage intervals and the measured value of each of the voltage intervals.

12 . A state of health (SOH) estimating method, as a battery management method based on at least one processor of an SOH estimating system, the SOH estimating method comprising:
determining a measured value of a time required for charging at each of preset voltage intervals within a preset voltage range in which a battery is charged with a constant current; determining an estimated value of a time required for charging at each of the voltage intervals according to a predicted SOH by a preset metamodel when a battery voltage is higher than the voltage range; and estimating a predicted SOH in which an error between the measured value and the estimated value based on a weighted least square (WLS) is the lowest, as a battery SOH.

13 . The SOH estimating method according to claim 12 , wherein, in the determining of the measured value, cells having the minimum, average, and maximum voltages are selected from among all the cells forming the battery, and a time required for charging at each of the voltage intervals of the three selected cells is measured.

14 . The SOH estimating method according to claim 13 , wherein, in the estimating, the battery SOH of each of the three selected cells is estimated, and an SOH of the cell having the maximum voltage is determined as the battery SOH.

15 . The SOH estimating method according to claim 12 , further comprising:
determining an initial time of a time required for charging by converting a result obtained by dividing a residual capacity by a charge current into a unit of second, before the battery is charged with a constant current.

16 . The SOH estimating method according to claim 15 , wherein the determining of the estimated value includes determining an estimated value of a time required for charging by changing a charge curve of the predicted SOH to correspond to the initial time.

17 . The SOH estimating method according to claim 12 , wherein the estimating includes:
determining an estimate value of a time required for charging at each of the voltage intervals corresponding to the predicted SOH by the metamodel; determining a residual vector by subtracting a measured value of each of the voltage intervals from the determined estimated value of each of the voltage intervals; and estimating the predicted SOH in which a weighted least square sum of the residual vector is minimized, as the battery SOH.

18 . The SOH estimating method according to claim 17 , wherein the predicted SOH is set to 1 initially when the battery starts to be charged, and sequentially reduced according to a number of updating the predicted SOH within a preset unit by the metamodel.

19 . The SOH estimating method according to claim 17 , wherein the estimating includes estimating the battery SOH, while updating the predicted SOH within a preset maximum repetition number and while updating the predicted SOH until the weighted least square sum of the residual vector is converged.

20 . The SOH estimating method according to claim 17 , wherein the weight value is set to be in inverse proportion to an error variance of the residual vector, a difference between the estimated value of a time required for charging at each of the voltage intervals and the measured value of each of the voltage intervals.

Assignees

• Hyundai Motor Co Ltd
• Kia Motors Corp

Inventors

• Sung Woo Suk

Classifications

• H02J7/00

  Circuit arrangements for charging or discharging batteries or for supplying loads from batteries · CPC title

• B60L53/665

  Methods related to measuring, billing or payment · CPC title

• G01R31/396

  Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery · CPC title

• B60Y2400/3084

  Electric currents sensors · CPC title

• G01R31/392 Primary

  Determining battery ageing or deterioration, e.g. state of health · CPC title