Battery parameter estimation

• US 9,197,078 B2
• Filed: 12/18/2013
• Issued: 11/24/2015
• Est. Priority Date: 12/18/2013
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Lee, Tae-Kyung
• Primary Examiner(s): Rodas, Richard Isla
• Assistant Examiner(s): Sharief, Mohammed Jameel
• Application Number:
  US14/132,046
• Publication Number:
  US 20150171640A1
• Time in Patent Office: 706 Days
• Field of Search: 320/109, 320/132, 324/429, 324/430, 324/434, 702/57, 702/60, 702 63- 65
• US Class Current: 1/1
• CPC Class Codes: B60L 2210/10 DC to DC converters
• CPC Class Codes: B60L 2210/40 DC to AC converters
• CPC Class Codes: B60L 2240/545 Temperature
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 2260/44 by parameter estimation
• CPC Class Codes: B60L 2260/50 by future state prediction
• CPC Class Codes: B60L 3/0046 relating to electric energy storage systems, e.g. batteries or capacitors
• CPC Class Codes: B60L 3/12 Recording operating variables ; Monitoring of operating variables
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/66 Arrangements of batteries
• CPC Class Codes: B60L 58/14 Preventing excessive discharging
• CPC Class Codes: B60L 58/15 Preventing overcharging
• CPC Class Codes: B60L 58/16 responding to battery ageing, e.g. to the number of charging cycles or the state of health [SoH]
• CPC Class Codes: B60L 58/20 having different nominal voltages
• CPC Class Codes: B60L 58/21 having the same nominal voltage
• CPC Class Codes: B60L 7/14 for vehicles propelled by ac motors
• 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 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: H02J 7/0013 : acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/0047 : with monitoring or indicating devices or circuits
• CPC Class Codes: H02J 7/0063 : with circuits adapted for supplying loads from the battery
• CPC Class Codes: H02J 7/00712 : the cycle being controlled or terminated in response to electric parameters
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility

Abstract

A vehicle includes a battery pack and at least one controller programmed to implement a model of the battery pack. The model includes parameters representing an internal resistance and charge transfer impedance of the battery pack, and identified from an extended Kalman filter having an augmented state vector. The augmented state vector is at least partially defined by a time constant associated with the charge transfer impedance and a variable representing a proportionality between the internal resistance and a resistance term of the charge transfer impedance to reduce observed variability of the parameters.

Claims

1. A vehicle comprising:

a battery pack; and

at least one controller programmed to

implement a model of the battery pack having parameters (i) representing an internal resistance and charge transfer impedance of the battery pack and (ii) identified from an extended Kalman filter having an augmented state vector at least partially defined by a time constant associated with the charge transfer impedance and a variable representing a quotient of a proportionality between the internal resistance and a resistance term of the charge transfer impedance to reduce observed variability of the parameters; and

control the battery pack in accordance with the parameters.

2. The vehicle of claim 1, wherein the charge transfer impedance is associated with at least one R-C circuit representation of the battery pack.

3. The vehicle of claim 1, wherein the at least one controller is further programmed to apply the augmented state vector to Jacobian matrices describing changes in battery parameter values of the model.

4. The vehicle of claim 1, wherein the augmented state vector further includes additional state variables representing battery dynamic responses or model parameters characterizing battery dynamics.

5. The vehicle of claim 1, wherein the at least one controller is further programmed to output power capability for a given time period based on the parameters.

6. A method comprising:

charging and discharging a battery pack based on parameters (i) representing an internal resistance and charge transfer impedance of the battery pack and (ii) identified from an extended Kalman filter having an augmented state vector partially defined by a time constant associated with the charge transfer impedance and a variable representing a quotient of a proportionality between the internal resistance and a resistance term of the charge transfer impedance reducing parameter variability.

7. The method of claim 6, wherein the charge transfer impedance is associated with at least one R-C circuit representation of the battery pack.

8. The method of claim 6, wherein the augmented state vector is applied to Jacobian matrices describing changes in battery parameter values of a dynamic model.

9. The method of claim 6, wherein the augmented state vector further includes additional state variables representing battery dynamic responses or model parameters characterizing battery dynamics.

10. A traction battery system comprising:

a battery pack having one or more cells;

at least one controller programmed to implement a model of the one or more cells having parameters identified by a filter at least partially defined by a variable representing a quotient of a proportionality between an internal resistance of the one of more cells and a resistance term of a charge transfer impedance of the one or more cells to reduce observed variability of the parameters; and

control the one or more cells in accordance with the parameters.

11. The system of claim 10, wherein the filter is further defined by a time constant associated with the charge transfer impedance.

12. The system of claim 10, wherein the charge transfer impedance is associated with at least one R-C circuit representation of the battery pack.