Systems and methods for determining battery system power capability
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.
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;
determining a peak power capability of the battery system based on the compensated ohmic resistance and the battery system model; and
implementing a control action in a vehicle associated with the battery system based on the determined peak power capability.
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 control action comprises an action associated with a regenerative braking acceptance setting of the vehicle.
9. The method of claim 1 , wherein the control action comprises an action associated with a maximum allowed vehicle acceleration.
10. The method of claim 1 , wherein the control action comprises an action associated with initiation of an electric drivetrain system of the vehicle.
11. 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, the method 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;
determining a peak power capability of the battery system based on the compensated ohmic resistance and the battery system model; and
implementing a control action in a vehicle associated with the battery system based on the determined peak power capability.
12. The non-transitory computer-readable medium of claim 11 , wherein the control action comprises an action associated with a regenerative braking acceptance setting of the vehicle.
13. The non-transitory computer-readable medium of claim 11 , 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 11 , 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 11 , 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.
18. The non-transitory computer-readable medium of claim 11 , wherein the control action comprises an action associated with a maximum allowed vehicle acceleration.
19. The non-transitory computer-readable medium of claim 11 , wherein the control action comprises an action associated with initiation of an electric drivetrain system of the vehicle.