Battery state estimation systems and methods using a nonlinear resistance element

• US 10,345,385 B2
• Filed: 10/20/2015
• Issued: 07/09/2019
• 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: Wampler, Charles W, Verbrugge, Mark W, Koch, Brian J, Laskowsky, Patricia M
• Primary Examiner(s): Pelton, Nathaniel R
• Assistant Examiner(s): Hernandez, Manuel
• Application Number:
  US14/887,926
• Publication Number:
  US 20160039419A1
• Time in Patent Office: 1,358 Days
• Field of Search: 320132, 324426
• CPC Class Codes: B60W 10/192 electric brakes
• CPC Class Codes: B60W 10/26 for electrical energy, e.g. batteries or capacitors
• CPC Class Codes: B60W 40/12 related to parameters of the vehicle itself , e.g. tyre models
• 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 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: H01M 10/4285 Testing apparatus
• 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 2220/20 Batteries in motive systems, e.g. vehicle, ship, plane
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Systems and methods are disclosed for estimating a state of a battery system such as a current-limited state of power and/or a voltage-limited state of power using a battery system model incorporating a nonlinear resistance element. Parameters of elements included in a battery cell model associated with a nonlinear resistance of a battery cell may be directly parameterized and used in connection with state estimation methods. By accounting for the nonlinear effect, embodiments of the disclosed systems and methods may increase available battery power utilized in connection with battery system control and/or management decisions over a larger window of operating conditions.

Claims

1. A method of estimating a state of a battery system, the method comprising:

measuring a terminal voltage of the battery system;

measuring a current and a temperature through the battery system;

determining parameters of a battery system model based, at least in part, on the measured terminal voltage of the battery system and the measured current through the battery system, the battery system model comprising at least one nonlinear element configured to model a nonlinear voltage to current response of the battery system, wherein determining the parameters of the battery system model comprises determining parameters associated with the at least one nonlinear element based, at least in part, on a piecewise polynomial approximation of the nonlinear voltage to current response of the battery system, wherein the piecewise polynomial approximation of the nonlinear voltage to current response partitions the nonlinear voltage to current response into regions based on the current and the temperature, with voltage being a polynomial function of the current and the temperature in each respective one of the regions;

determining a predicted battery system voltage based, at least in part, on the battery system model;

estimating the state of the battery system based on the predicted battery system voltage; and

implementing a control action in a vehicle associated with the battery system based on the estimated battery system state, wherein the control action comprises at least one of adjusting a maximum allowed acceleration of the vehicle, adjusting initiation of an electric drivetrain system of the vehicle, and adjusting a regenerative braking acceptance setting of the vehicle.

2. The method of claim 1, wherein the state of the battery system comprises a state of power of the battery system.

3. The method of claim 2, wherein the state of the battery system comprises a current-limited state of power of the battery system.

4. The method of claim 2, wherein the state of the battery system comprises a voltage-limited state of power of the battery system.

5. The method of claim 1, wherein the state of the battery system comprises a state of charge of the battery system.

6. The method of claim 1, wherein the battery system model comprises an equivalent circuit model and the nonlinear element comprises a nonlinear resistor.

7. The method of claim 6, wherein the nonlinear element further comprises a linear capacitor disposed in parallel with the nonlinear resistor.

8. The method of claim 1, wherein the battery system model further comprises an element modeling an open circuit voltage of the battery system and a linear element disposed in series with the nonlinear element.

9. The method of claim 8, wherein the linear element comprises a plurality of serially coupled parallel resistor capacitor pairs.

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

11. The method of claim 1, wherein determining the parameters of the battery system model further comprises determining parameters associated with the at least one nonlinear element based further, at least in part, on a Butler-Volmer model describing the kinetics of charge transfer in the battery system.

12. A non-transitory computer-readable medium storing instructions that, when executed by a processor, cause the processor to perform a method of estimating a state of a battery system comprising:

measuring a terminal voltage of the battery system;

measuring a current and a temperature through the battery system;

determining parameters of a battery system model based, at least in part, on the measured terminal voltage of the battery system and the measured current through the battery system, the battery system model comprising at least one nonlinear element configured to model a nonlinear voltage to current response of the battery system, wherein determining the parameters of the battery system model comprises determining parameters associated with the at least one nonlinear element based, at least in part, on a piecewise polynomial approximation of the nonlinear voltage to current response of the battery system, the piecewise polynomial approximation of the nonlinear voltage to current response partitions the nonlinear voltage to current response into regions based on the current and the temperature, with voltage being a polynomial function of the current and the temperature in each respective one of the regions;

determining a predicted battery system voltage based, at least in part, on the battery system model;

estimating the state of the battery system based on the predicted battery system voltage; and

implementing a control action in a vehicle associated with the battery system based on the estimated battery system state, wherein the control action comprises at least one of adjusting a maximum allowed acceleration of the vehicle, adjusting initiation of an electric drivetrain system of the vehicle, and adjusting a regenerative braking acceptance setting of the vehicle.

13. The non-transitory computer-readable medium of claim 12, wherein determining the parameters of the battery system model further comprises determining parameters associated with the at least one nonlinear element based further, at least in part, on a Butler-Volmer model describing the kinetics of charge transfer in the battery system.