Estimation and compensation of battery measurement and asynchronization biases

• US 9,555,718 B2
• Filed: 12/06/2013
• Issued: 01/31/2017
• Est. Priority Date: 12/06/2013
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Li, Yonghua, Anderson, Richard Dyche
• Primary Examiner(s): Mawari, Redhwan K
• Assistant Examiner(s): Torchinsky, Edward
• Application Number:
  US14/099,056
• Publication Number:
  US 20150158395A1
• Time in Patent Office: 1,152 Days
• Field of Search: None
• US Class Current: 1/1
• 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 58/12 responding to state of charge [SoC]
• CPC Class Codes: B60L 58/21 having the same nominal voltage
• CPC Class Codes: B60W 10/26 for electrical energy, e.g. batteries or capacitors
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: B60W 2710/248 Current for loading or unloading
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: G01R 31/396 Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
• CPC Class Codes: H01M 10/482 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/486 for measuring temperature
• 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

Abstract

A hybrid or electric vehicle includes a traction battery to store and provide energy for the vehicle. The traction battery includes a number of battery cells. For effective operation of the traction battery, operating parameters, such as state of charge and battery power limits, may need to be known. The operating parameters may be a function of battery cell voltage and impedance parameters. A parameter estimation scheme may use measured cell voltages and a measured traction battery current as inputs. A current measurement bias may be modeled that incorporates measurement bias caused by asynchronous current and voltage measurements. The current measurement bias may be estimated for each cell and the value may differ between cells.

Claims

1. A vehicle comprising:

a traction battery including a plurality of cells; and

at least one controller programmed to implement a state estimator configured to estimate, for each cell, a current measurement bias specific to the cell that depends on a temporal difference between current and voltage measurements for the cell, and operate the traction battery according to a state of charge derived from voltage parameters that are based on the current measurement bias.

2. The vehicle of claim 1 wherein the at least one controller is further programmed to control the traction battery according to battery power limits defined by output of the state estimator.

3. The vehicle of claim 1 wherein at least some of the current measurement biases have different values.

4. The vehicle of claim 1 wherein the voltage parameters include an open circuit voltage for the cell.

5. The vehicle of claim1 wherein the state estimator is further configured to output, for each cell, impedance parameters based on the current measurement bias specific to the cell.

6. The vehicle of claim 5 wherein the impedance parameters include a resistance associated with the cell.

7. The vehicle of claim 1 wherein the state estimator is further configured to apply a forgetting factor to the current measurement bias.