Control device and method for discharging a rechargeable battery

Patent metadata

Field	Value
Publication number	US-11225166-B2
Application number	US-201616070905-A
Country	US
Kind code	B2
Filing date	Feb 2, 2016
Priority date	Feb 2, 2016
Publication date	Jan 18, 2022
Grant date	Jan 18, 2022

Abstract

A control device for controlling discharging of a rechargeable battery, the control device comprising a rechargeable dummy cell, a first circuit configured to discharge the battery and the dummy cell, and a second circuit configured to measure the open circuit voltage of the dummy cell. The control device is configured to: determine the open circuit voltage of the dummy cell by using the second circuit, and determine the maximum capacity decrement of the battery, which is to be discharged until full discharging, based on the determined open circuit voltage of the dummy cell. The invention also refers to a corresponding method of controlling discharging of a rechargeable battery.

First claim

The invention claimed is:

1. A control device for controlling discharging of a rechargeable battery, comprising:
a rechargeable dummy cell,
a first circuit configured to discharge the battery and the dummy cell, and
a second circuit, configured to measure the open circuit voltage of the dummy cell,
the control device being configured to:
determine the open circuit voltage of the dummy cell by using the second circuit,
determine a maximum capacity decrement of the battery based on the determined open circuit voltage of the dummy cell,
determine, whether the battery is charged during discharging, and
if yes, re-determine the open circuit voltage of the dummy cell and the maximum capacity decrement of the battery.

2. The control device according to claim 1 , further configured to:
discharge the battery and the dummy cell by using the first circuit,
monitor the current capacity decrement of the battery which has been discharged and the voltage of the battery, and
stop discharging, when the current capacity decrement of the battery exceeds the determined maximum capacity decrement or the voltage falls below a predetermined lower voltage limit.

3. The control device according to claim 1 , further configured to:
determine the current capacity decrement of the battery based on the discharging current and the discharging time of the battery, and/or based on the open circuit voltage of the dummy cell.

4. The control device according to claim 1 , further configured to:
determine the state of charge of the dummy cell based on the determined open circuit voltage of the dummy cell, and
determine the maximum capacity decrement based on the determined state of charge of the dummy cell.

5. The control device according to claim 4 , further configured to update the predetermined SOC-OCV mapping based on a determined degradation of the dummy cell.

6. The control device according to claim 5 , further configured to determine the degradation of the dummy cell based on a temperature/frequency distribution of the dummy cell and a predetermined degradation rate of the dummy cell.

7. The control device according to claim 5 , wherein
the determination of the degradation of the dummy cell is based on the Arrhenius equation.

8. The control device according to claim 5 , further configured to determine the temperature/frequency distribution of the dummy cell by recording for each temperature of the dummy cell how much time the dummy cell had this temperature during its lifetime.

9. The control device according to claim 4 , further configured to:
determine the state of charge of the battery based on the determined state of charge of the dummy cell and based on a predetermined mapping between the state of charge of the battery and the state of charge of the dummy cell, and
determine the maximum capacity decrement based on the state of charge of the battery.

10. The control device according to claim 1 , configured to control discharging of a battery of a specific battery type comprising a predetermined degradation rate,
wherein the dummy cell has a degradation rate which correlates with the degradation rate of the battery.

11. The control device according to claim 1 , wherein the battery of the specific battery type comprises a predetermined capacity,
wherein the dummy cell has a capacity which correlates with the capacity of the battery.

12. The control device according to claim 1 , comprising a voltage sensor for detecting the open circuit voltage of the dummy cell.

13. The control device according to claim 1 , comprising a temperature sensor for detecting the temperature of the dummy cell and/or the battery.

14. A battery pack comprising:
at least one battery, and
a control device according to claim 1 .

15. A vehicle comprising:
an electric motor, and
a battery pack according to claim 14 .

16. A battery discharging system comprising:
at least one battery,
a discharging device for the battery, and
a control device according to claim 1 .

17. A vehicle comprising:
an electric motor,
at least one battery, and
a control device according to claim 1 .

18. A method of controlling discharging of a rechargeable battery, wherein a first circuit is used to discharge the battery and a rechargeable dummy cell, and a second circuit is used to measure the open circuit voltage of the dummy cell, the method comprising the steps of:
determining the open circuit voltage of the dummy cell by using the second circuit,
determining a maximum capacity decrement of the battery based on the determined open circuit voltage of the dummy cell,
determining, whether the battery is charged during discharging, and,
if yes, re-determining the open circuit voltage of the dummy cell and the maximum capacity decrement.

19. The method according to claim 18 , further comprising the steps of:
discharging the battery and the dummy cell by using the first circuit,
monitoring the current capacity decrement of the battery which has been discharged and the voltage of the battery, and
stopping discharging, when the current capacity decrement of the battery exceeds the determined maximum capacity decrement or the voltage falls below a predetermined lower voltage limit.

20. The method according to claim 18 , wherein the current capacity decrement of the battery is determined based on the discharging current and the discharging time of the battery, and/or based on the open circuit voltage of the dummy cell.

21. The method according to claim 18 , wherein the state of charge of the dummy cell is determined based on the determined open circuit voltage of the dummy cell, and
the maximum capacity decrement is determined based on the determined state of charge of the dummy cell.

22. The method according to claim 21 , wherein the predetermined SOC-OCV mapping is updated based on a determined degradation of the dummy cell.

23. The method according to claim 22 , wherein the degradation of the battery is determined based on a temperature/frequency distribution of the dummy cell and a predetermined degradation rate of the dummy cell.

24. The method according to claim 23 , wherein the temperature/frequency distribution of the dummy cell is determined by recording for each temperature of the dummy cell how much time the dummy cell had this temperature during its lifetime.

25. The method according to claim 22 , wherein the determination of the degradation of the dummy cell is based on the Arrhenius equation.

26. The method according to claim 21 , wherein
the state of charge of the battery is determined based on the determined state of charge of the dummy cell and based on a predetermined mapping between the state of charge of the battery and the state of charge of the dummy cell, and
the maximum capacity decrement is determined based on the state of charge of the battery.

27. A control device for controlling discharging of a rechargeable battery, comprising:
a rechargeable dummy cell,
a first circuit configured to discharge the battery and the dummy cell, and
a second circuit configured to measure the open circuit voltage of the dummy cell,
the control device being configured to:
determine the open circuit voltage of the dummy cell by using the second circuit,
determine a maximum capacity decrement of the battery based on the determined open circuit voltage of the dummy cell,
determine, whet

Assignees

• Toyota Motor Europe

Inventors

• Komiyama Keita
• Katoh Yuki

Classifications

• H02J2105/37

  exchanging power with electric vehicles [EV] or with hybrid electric vehicles [HEV] · CPC title

• H02J7/825

  Detection of fully charged condition · CPC title

• H02J7/585

  Sequential battery discharge in systems with a plurality of batteries · CPC title

• H02J7/96

  in response to battery voltage · CPC title

• H02J7/84

  Control of state of health [SOH] · CPC title