IMPEDANCE BASED BATTERY PARAMETER ESTIMATION

• US 20150197159A1
• Filed: 01/14/2014
• Published: 07/16/2015
• Est. Priority Date: 01/14/2014
• 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
• Granted Patent: US 9,428,071 B2
• Time in Patent Office: Days
• 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 2240/80 Time limits
• CPC Class Codes: B60L 2260/44 by parameter estimation
• CPC Class Codes: B60L 3/0046 relating to electric energy storage systems, e.g. batteries or capacitors
• CPC Class Codes: B60L 3/04 Cutting off the power supply under fault conditions protective devices and circuit arrangements in general H01H; H02H
• 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 58/10 for monitoring or controlling 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: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• 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
• CPC Class Codes: Y10S 903/903 : having energy storing means, e.g. battery, capacitor

Abstract

A hybrid powertrain system includes a battery cell and at least one controller programmed to output an average internal resistance of the cell for a sliding window time period. A mean electrical impedance is calculated by the controller based on a quotient of a Fast Fourier Transform (FFT) of a voltage output by the cell and a FFT of current input to the cell. An average internal resistance is calculated by the controller based on the mean electrical impedance. The controller may further control the cell according to the average internal resistance.

Claims

1. A vehicle comprising:

a battery pack having one or more battery cells; and

at least one controller programmed to

output a mean electrical impedance of the one or more cells for a sliding window time period based on a quotient of a Fast Fourier Transform (FFT) of voltage output by the one or more cells and a FFT of current input to the one or more cells,

output an average internal resistance of the one or more cells for the time period based on a magnitude of a real component of the mean electrical impedance if a magnitude of a ratio of an imaginary component of the mean electrical impedance and the real component is less than or equal to a predetermined value,

output an average internal resistance of the one or more cells for the time period based on a product of a correction factor and the magnitude of the real component if the magnitude of the ratio is greater than the predetermined value, and

control operation of the battery pack according to the average internal resistance.

2. The vehicle of claim 1, wherein the correction factor is proportional to a ratio of the mean electrical impedance and the real component.

3. The vehicle of claim 1, wherein the at least one controller is further programmed to output a maximum discharge power available based on the average internal resistance.

4. The vehicle of claim 1, wherein the at least one controller is further programmed to output a maximum charge power available based on the average internal resistance.

5. The vehicle of claim 1, wherein the predetermined value ranges from 0.1 to 0.5.

6. A hybrid powertrain system comprising:

a battery cell; and

at least one controller programmed to output a mean electrical impedance of the cell for a sliding window time period based on a quotient of a Fast Fourier Transform (FFT) of voltage output by the cell and a FFT of current input to the cell, and control operation of the cell according to the mean electrical impedance.

7. The hybrid powertrain system of claim 6, wherein the at least one controller is further programmed to output an average internal resistance of the cell for the time period based on a magnitude of a real component of the mean electrical impedance if a magnitude of a ratio of an imaginary component of the mean electrical impedance and the real component is less than or equal to a predetermined value, and control operation of the cell according to the average internal resistance.

8. The hybrid powertrain system of claim 7, wherein the at least one controller is further programmed to output an average internal resistance of the cell for the time period based on a product of a correction factor and the magnitude of the real component if the magnitude of the ratio is greater than a predetermined value, and control operation of the cell according to the average internal resistance.

9. The hybrid powertrain system of claim 8, wherein the at least one controller is further programmed to output a power available for the time period based on the average internal resistance.

10. The hybrid powertrain system of claim 8, wherein the predetermined value is approximately 0.45.

11. The hybrid powertrain system of claim 8, wherein the correction factor is proportional to a ratio of a magnitude of the mean electrical impedance and the real component.

12. A method comprising:

outputting a mean electrical impedance of a traction battery for a sliding window time period based on a quotient of a Fast Fourier Transform (FFT) of voltage output by the battery and a FFT of current input to the battery,

outputting an average internal resistance of the battery for the time period based on a magnitude of a real component of the mean electrical impedance if a magnitude of a ratio of an imaginary component of the mean electrical impedance and the real component is less than or equal to a predetermined value,

outputting an average internal resistance of the battery for the time period based on a product of a correction factor and the magnitude of the real component if the magnitude of the ratio is greater than the predetermined value, and

controlling operation of the battery according to the average internal resistance.

13. The method of claim 12, wherein the correction factor is proportional to a ratio of a magnitude of the mean electrical impedance and the real component.

14. The method of claim 12 further comprising outputting a maximum discharge power available for the time period based on the average internal resistance.

15. The method of claim 12 further comprising outputting a maximum charge power available for the time period based on the average internal resistance.