BATTERY STATE-OF-CHARGE ESTIMATION

• US 20130257377A1
• Filed: 03/29/2012
• Published: 10/03/2013
• Est. Priority Date: 03/29/2012
• Status: Active Grant

• Current Assignee: Atieva, Inc.
• Original Assignee: Albert Shih-Young Liu
• Inventors: Diamond, Steven, Risk, Gabriel, Liu, Albert Shih-Young, Hu, Stanley, Helliwell, Martin
• Granted Patent: US 10,690,725 B2
• Time in Patent Office: Days
• US Class Current: 320/118
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]

Abstract

A battery pack management system adjusts the relative state-of-charge of respective battery blocks in a battery pack to equalize (i.e., align, balance or otherwise make similar) the peak battery block voltages (i.e., maximum or “upper peak” battery block voltages when the battery pack is being charged and/or minimum or “lower peak” battery block voltages when the battery is being discharged). Upon detecting an anomalous battery block that exhibits outlier upper and lower peak voltages, the battery pack management system adjusts the relative state of charge of respective battery blocks to center their respective upper and lower peak voltages between operating limits, thus maximizing the operating margin of the battery pack as a whole.

Claims

1. A method of operation within a battery system having a plurality of battery blocks coupled in series between terminals of a battery pack, the method comprising:

charging the battery blocks during a first interval;

measuring respective charging voltages of the battery blocks while charging the battery blocks; and

determining a state-of-charge of the battery pack based, at least in part, on the charging voltages of the battery blocks.

2. The method of claim 1 wherein charging the battery blocks comprises supplying a current pulse to the battery pack via the battery pack terminals.

3. The method of claim 1 wherein charging the battery blocks comprises supplying current from a regenerative braking system within a hybrid electric vehicle or an electric vehicle to the battery pack via the battery pack terminals.

4. The method of claim 1 wherein measuring respective charging voltages of the battery blocks during the first interval comprises measuring each of the battery block voltages concurrently.

5. The method of claim 1 wherein determining a state-of-charge comprises identifying a first battery block of the battery blocks that has a charging voltage higher than at least a second battery block of the battery blocks and discharging the first battery block to reduce the difference between the charging voltages of the first and second battery blocks.

6. The method of claim 5 wherein discharging the first battery block comprises switchably coupling balance resistors to the battery block.

7. The method of claim 1 further comprising displaying the state-of-charge of the battery pack to the operator of a hybrid electric vehicle or an electric vehicle.

8. The method of claim 1 further comprising determining a driving range of a hybrid electric vehicle or an electric vehicle based, at least in part, on the state-of-charge of the battery pack.

9. The method of claim 8 further comprising displaying the driving range to the operator of the hybrid electric vehicle or the electric vehicle.

10. The method of claim 1 wherein determining the state-of-charge of the battery pack based, at least in part, on the charging voltages of the battery blocks comprises:

measuring respective open-circuit voltages of the battery blocks;

generating an initial estimate of the state-of-charge of the battery pack based on the open-circuit voltages of the battery blocks; and

adjusting the initial estimate of the state-of-charge of the battery pack based, at least in part, on the charging voltages of the battery blocks.

11. A method of operation within a battery system having a plurality of battery blocks coupled in series between terminals of a battery pack, the method comprising:

discharging the battery blocks during a first interval;

measuring respective discharging voltages of the battery blocks while discharging the battery blocks; and

determining a state-of-charge of the battery pack based, at least in part, on the discharging voltages of the battery blocks.

12. A battery management system to control a battery system having a plurality of battery blocks coupled in series between terminals of a battery pack, the battery management system comprising:

one or more voltage measurement inputs to receive respective charging voltage measurements of the battery blocks while the battery blocks are being charged; and

state-of-charge determination logic to determine a state-of-charge of the battery pack based, at least in part, on the charging voltage measurements received via the voltage measurement inputs.

13. The battery management system of claim 12 wherein the state-of-charge determination logic further comprises outputs that indicate a state-of-charge of each of the respective battery blocks in the battery pack.

14. The battery management system of claim 12 wherein the battery system is disposed within an electric/hybrid-electric vehicle.

15. The battery management system of claim 12 wherein the number of charging voltage measurement inputs is equal to the number of battery blocks.

16. The battery management system of claim 12 wherein the state-of-charge determination logic is implemented at least in part by a programmed processor.

17. The battery management system of claim 12 wherein the battery system is disposed within an electric/hybrid-electric vehicle, the battery management system further comprising an output to provide a value corresponding to the state-of-charge of the battery pack to an operator display device disposed within the hybrid electric vehicle or the electric vehicle, the operator display device to display information corresponding to the state-of-charge of the battery pack to an operator of the electric/hybrid-electric vehicle.

18. The battery management system of claim 12 wherein the battery system is disposed within an electric/hybrid-electric vehicle, the battery management system further comprising driving range determination logic to determine, based at least in part on a value received from the state-of-charge determination logic that indicates the state-of-charge of the battery pack, a driving range of electric/hybrid-electric vehicle.

19. The battery system apparatus of claim 18 further comprising an output to provide a value corresponding to the driving range of the electric/hybrid-electric vehicle to an operator display device disposed within the electric/hybrid-electric vehicle, the operator display device to display information corresponding to the value corresponding to the driving range to an operator of the electric/hybrid-electric vehicle.

20. A battery management system to control a battery system having a plurality of battery blocks coupled in series between terminals of a battery pack, the battery management system comprising:

means for receiving respective charging voltage measurements of the battery blocks while the battery blocks are being charged; and

means for determining a state-of-charge of the battery pack based, at least in part, on the charging voltage measurements received via the means for receiving.