SYSTEMS AND METHODS FOR DETERMINING BATTERY SYSTEM POWER CAPABILITY

• US 20150321572A1
• Filed: 05/12/2014
• Published: 11/12/2015
• Est. Priority Date: 05/12/2014
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: KOCH, BRIAN J., FRISCH, DAMON R., STAWINSKI, BRETT B., FROST, PATRICK, NOVAK, JOHN E.
• Granted Patent: US 9,419,314 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60L 15/20 for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
• CPC Class Codes: B60L 15/2009 for braking
• CPC Class Codes: B60L 58/10 for monitoring or controlling batteries
• CPC Class Codes: G01R 21/14 Compensating for temperature change
• CPC Class Codes: G01R 31/36 Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
• CPC Class Codes: G01R 31/3647 for determining the ability of a battery to perform a critical function, e.g. cranking
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/374 with means for correcting the measurement for temperature or ageing
• CPC Class Codes: G01R 31/3828 using current integration
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: H01M 10/425 Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing printed circuits H05K1/00
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H01M 10/482 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 2010/4278 Systems for data transfer from batteries, e.g. transfer of battery parameters to a controller, data transferred between battery controller and main controller
• CPC Class Codes: H01M 2220/20 Batteries in motive systems, e.g. vehicle, ship, plane
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

System and methods for determining battery system power capability in a vehicle are presented. Peak power capability estimation systems and methods disclosed herein may compensate regressed parameters in a battery system circuit model for an effect of current magnitude. Utilizing the disclosed methods for accurately estimating peak power capability of a battery system may provide for, among other things, improved battery system performance modeling and/or improved battery system control and management decisions.

Claims

1. A method of determining a peak power capability of a battery system comprising:

identifying a peak current of the battery system;

determining a regressed ohmic resistance in a battery system model used to model the battery system;

scaling the regressed ohmic resistance to calculate a compensated ohmic resistance of the battery system model based on the peak current; and

determining a peak power capability of the battery system based on the compensated ohmic resistance and the battery system model.

2. The method of claim 1, wherein the peak power capability comprises a current-limited peak power capability and the peak current of the battery system comprises a maximum current limit of the battery system.

3. The method of claim 1, wherein the peak power capability comprises a voltage-limited peak power capability and identifying the peak current comprises:

generating a guessed current;

determining a guessed resistance based on the guessed current using current dependent resistance information;

determining a calculated current based on the guessed resistance; and

determining whether a difference between the calculated current and the guessed current is below a threshold.

4. The method of claim 3, wherein if the difference between the calculated current and the guessed current is below the threshold, identifying the peak current comprises:

identifying the calculated current as the peak current.

5. The method of claim 3, wherein if the difference between the calculated current and the guessed current is not below the threshold, identifying the peak current comprises:

iteratively generating subsequent guessed currents, determining subsequent guessed resistances based on the subsequent guessed currents, and determining subsequent calculated currents based on the subsequent guessed currents until a difference between a final subsequent calculated current and a final subsequent guessed current is below the threshold; and

identifying the final subsequent calculated current as the peak current.

6. The method of claim 1, wherein scaling the regressed ohmic resistance to calculate a compensated ohmic resistance further comprises:

determining a peak resistance based on the peak current;

determining a nominal resistance based on an average current associated with a regression operation used to calculate the regressed ohmic resistance; and

scaling the regressed ohmic resistance by a ratio of the peak resistance to the nominal resistance to calculate the compensated ohmic resistance.

7. The method of claim 1, wherein the model comprises a circuit model including elements configured to model ohmic resistance, charge transfer, and mass transfer processes of the battery system.

8. The method of claim 1, wherein the method further comprises:

implementing a control action in a vehicle associated with the battery system based on the determined peak power capability.

9. The method of claim 8, wherein the control action comprises an action associated with a maximum allowed vehicle acceleration.

10. The method of claim 8, wherein the control action comprises an action associated with initiation of an electric drivetrain system of the vehicle.

11. The method of claim 8, wherein the control action comprises an action associated with a regenerative braking acceptance setting of the vehicle.

12. A non-transitory computer-readable medium comprising instructions that, when executed by a processor, cause the processor to perform a method of determining a peak power capability of a battery system:

identifying a peak current of the battery system;

determining a regressed ohmic resistance in a battery system model used to model the battery system;

scaling the regressed ohmic resistance to calculate a compensated ohmic resistance of the battery system model based on the peak current; and

determining a peak power capability of the battery system based on the compensated ohmic resistance and the battery system model.

13. The non-transitory computer-readable medium of claim 12, wherein the peak power capability comprises a current-limited peak power capability and the peak current of the battery system comprises a maximum current limit of the battery system.

14. The non-transitory computer-readable medium of claim 12, wherein the peak power capability comprises a voltage-limited peak power capability and identifying the peak current comprises:

generating a guessed current;

determining a guessed resistance based on the guessed current using current dependent resistance information;

determining a calculated current based on the guessed resistance; and

determining whether a difference between the calculated current and the guessed current is below a threshold.

15. The non-transitory computer-readable medium of claim 14, wherein if the difference between the calculated current and the guessed current is below the threshold, identifying the peak current comprises:

identifying the calculated current as the peak current.

16. The non-transitory computer-readable medium of claim 14, wherein if the difference between the calculated current and the guessed current is not below the threshold, identifying the peak current comprises:

iteratively generating subsequent guessed currents, determining subsequent guessed resistances based on the subsequent guessed currents, and determining subsequent calculated currents based on the subsequent guessed currents until a difference between a final subsequent calculated current and a final subsequent guessed current is below the threshold; and

identifying the final subsequent calculated current as the peak current.

17. The non-transitory computer-readable medium of claim 12, wherein scaling the regressed ohmic resistance to calculate a compensated ohmic resistance further comprises:

determining a peak resistance based on the peak current;

determining a nominal resistance based on an average current associated with a regression operation used to calculate the regressed ohmic resistance; and

scaling the regressed ohmic resistance by a ratio of the peak resistance to the nominal resistance to calculate the compensated ohmic resistance.