State of health estimation for batteries

Patent metadata

Field	Value
Publication number	US-11101669-B2
Application number	US-201916535186-A
Country	US
Kind code	B2
Filing date	Aug 8, 2019
Priority date	Feb 9, 2017
Publication date	Aug 24, 2021
Grant date	Aug 24, 2021

Abstract

A method for determining a state of health of a rechargeable battery includes: determining a change in charge within an upper border and a lower border of a charging state window, the change in charge being determined by summing up current values measured within the charging state window; determining an actual state of health by scaling the change in charge with the width of the charging state window and dividing by an initial charging capacity of the battery; and determining an average state of health by calculating a sliding average of the actual state of health with at least one previous determined state of health.

First claim

The invention claimed is:

1. A method for determining a state of health of a rechargeable battery, the method comprising:
determining a change in charge within an upper border and a lower border of a charging state window, the change in charge being determined by summing up current values measured within the charging state window;
determining an actual state of health by scaling the change in charge with the width of the charging state window and dividing by an initial charging capacity of the battery;
determining an averaged state of health by calculating a sliding average of the actual state of health with at least one previous determined state of health;
wherein during determining of the change in charge, an average current is determined by measuring battery current values and calculating an average of these values;
wherein the initial charging capacity is multiplied with a correction factor dependent on the average current for adapting the initial charging capacity, which has been determined for a reference current, to the average current.

2. The method of claim 1 ,
wherein a charging state used for determining, whether the charging state window has been entered and has been left, is determined based on additional measurements with respect to the battery.

3. The method of claim 2 ,
wherein the additional measurements include a voltage across the battery and/or a temperature of the battery.

4. The method of claim 1
wherein the change in charge is determined during charging of the battery, when a charging state of the battery is increasing.

5. The method of claim 1 ,
wherein the change in charge is determined during discharging of the battery, when a charging state of the battery is decreasing.

6. The method of claim 1 ,
wherein during determining of the change in charge, an average temperature is determined;
wherein the initial charging capacity is multiplied with a correction factor dependent on the average temperature and the average current for adapting the initial charging capacity, which has been determined for a reference temperature and/or a reference current, to the average temperature and/or average current.

7. The method of claim 6 ,
wherein the average temperature is determined by measuring battery temperature values and calculating an average of these values.

8. The method of claim 1 ,
wherein the correction factor is taken from a lookup table referenced by temperature and/or current.

9. The method of claim 1 ,
wherein the borders of the charging state window are fixed values;
wherein the upper border is set between 90% and 50% of a charging capacity;
wherein the lower border is set between 70% and 30% of a charging capacity.

10. The method of claim 1 ,
wherein the charging state window has a width of a least 25% of a charging capacity.

11. The method of claim 1 ,
wherein the determination of the state of health is regularly repeated; and/or
wherein the determination of the state of health is repeated at least every 10 charging cycles; and/or
wherein the determination of the state of health is only performed, when a temperature during determination of the change in charge is higher than a lowest temperature.

12. The method of claim 1 , further comprising:
determining an upper threshold temperature for the battery from the averaged state of health;
controlling the charging and decharging of the battery, such that a temperature of the battery is lower than the upper threshold temperature.

13. The method of claim 2 , wherein the change in charge is determined during charging of the battery, when a charging state of the battery is increasing.

14. The method of claim 2 , wherein the change in charge is determined during discharging of the battery, when a charging state of the battery is decreasing.

15. The method of claim 2 , wherein during determining of the change in charge, an average temperature is determined;
wherein the initial charging capacity is multiplied with a correction factor dependent on the average temperature and the average current for adapting the initial charging capacity, which has been determined for a reference temperature and/or a reference current, to the average temperature and/or average current.

16. The method of claim 15 , wherein the average temperature is determined by measuring battery temperature values and calculating an average of these values.

17. The method of claim 2 , wherein the correction factor is taken from a lookup table referenced by temperature and/or current.

18. A battery controller structured to determine a state of health of a rechargeable battery, the battery controller operable to execute instructions comprising:
determine a change in charge within an upper border and a lower border of a charging state window, the change in charge being determined by summing up current values measured within the charging state window;
determine an actual state of health by scaling the change in charge with the width of the charging state window and dividing by an initial charging capacity of the battery;
determine an averaged state of health by calculating a sliding average of the actual state of health with at least one previous determined state of health;
wherein during determining of the change in charge, an average current is determined by measuring battery current values and calculating an average of these values;
wherein the initial charging capacity is multiplied with a correction factor dependent on the average current for adapting the initial charging capacity, which has been determined for a reference current, to the average current.

19. A method for determining the state of health of a fleet of rechargeable batteries, the method comprising:
receiving a state of health of one of the batteries of the fleet of batteries in a central database, the state of health being determined by acts including:
determining a change in charge within an upper border and a lower border of a charging state window, the change in charge being determined by summing up current values measured within the charging state window;
determining an actual state of health by scaling the change in charge with the width of the charging state window and dividing by an initial charging capacity of the battery;
determining an averaged state of health by calculating a sliding average of the actual state of health with at least one previous determined state of health;
wherein during determining of the change in charge, an average current is determined by measuring battery current values and calculating an average of these values;
wherein the initial charging capacity is multiplied with a correction factor dependent on the average current for adapting the initial charging capacity, which has been determined for a reference current, to the average current;
comparing the state of health with a threshold value, and, when the state of health is below the threshold value, scheduling a replacement of the battery;
sending information about the scheduled replacement to a battery supplier and/or to an owner of the battery.

20. A battery management system, comprising:
a central server including a central database structured to receive a state of health of one of the batteries of a fleet of batteries;
at least one battery charging controller operable to execute instructions comprising:
determine a change in charge within an upper border and a lower border of a charging state window, the change in charge being determined by summing up current values mea

Assignees

• Abb Schweiz Ag

Inventors

• Patey Timothy
• Flueckiger Reto
• Sologubenko Oleksandr
• Zgraggen Andreas

Classifications

• G01R31/392 Primary

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

• G01R31/3832

  without measurement of battery voltage · CPC title

• G01R31/367

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

• G01R31/3842

  combining voltage and current measurements · CPC title

• H02J7/0021 Primary

  Electricity · mapped topic