Current sensor for a vehicle

• US 9,656,570 B2
• Filed: 12/15/2014
• Issued: 05/23/2017
• Est. Priority Date: 12/15/2014
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Tabatowski-Bush, Benjamin A.
• Primary Examiner(s): Memula, Suresh
• Application Number:
  US14/570,117
• Publication Number:
  US 20160167540A1
• Time in Patent Office: 890 Days
• Field of Search: 320136
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 53/14 Conductive energy transfer
• CPC Class Codes: B60L 58/15 Preventing overcharging
• 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 90/12 Electric charging stations
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles
• CPC Class Codes: Y02T 90/16 Information or communication technologies improving the operation of electric vehicles

Abstract

A vehicle includes a battery configured to operate at a current, during a drive cycle, in a nominal current range for a time greater than in a maximum current range. A controller is programmed to output a voltage based on the current according to a gain calibrated to be greater in the nominal current range than in the maximum current range to increase resolution in the nominal current range. The gain may be based on an exponential function or piecewise linear function of the current. The gain may increase as a magnitude of the current increases. A second controller receives the voltage and derives a battery current according to an inverse of the gain.

Claims

1. A vehicle comprising:

a battery configured to operate at a current, during a drive cycle, in a nominal current range for a time greater than in a maximum current range; and

a controller programmed to change an output voltage, in response to a change in the current, by a greater amount when the current is in the nominal current range than when the current is in the maximum current range.

2. The vehicle of claim 1 wherein the output voltage is defined by an exponential function of the current.

3. The vehicle of claim 1 wherein the output voltage is defined by a piecewise linear function of the current.

4. The vehicle of claim 1 wherein the output voltage is defined such that a ratio between a change in the output voltage and the change in the current decreases as a magnitude of the current increases.

5. The vehicle of claim 1 further comprising a second controller programmed to receive the output voltage and operate the battery according to a battery current derived from the output voltage.

6. The vehicle of claim 5 wherein the battery current is derived from the output voltage based on an inverse of a gain that defines the output voltage as a function of the current.

7. The vehicle of claim 5 wherein the second controller is further programmed to, in response to conditions indicative of the current being zero, measure a zero current voltage and further derive the battery current based on the zero current voltage.

8. A battery management system comprising:

a controller programmed to measure a current from a battery configured to operate, during a drive cycle, at the current in a nominal current range for a time greater than in a maximum current range, and change a voltage, in response to a change in the current, by a greater amount when the current is in the nominal current range than when the current is in the maximum current range.

9. The battery management system of claim 8 wherein the voltage is defined by an exponential function of the current.

10. The battery management system of claim 8 wherein the voltage is defined by a piecewise linear function of the current.

11. The battery management system of claim 8 wherein the voltage is defined such that a ratio between a change in the voltage and the change in the current decreases as a magnitude of the current increases.

12. The battery management system of claim 8 further comprising a second controller programmed to receive the voltage and operate the battery according to a battery current derived from the voltage.

13. The battery management system of claim 12 wherein the battery current is derived from the voltage based on an inverse of a gain that defines the voltage as a function of the current.

14. The battery management system of claim 12 wherein the second controller is further programmed to, in response to conditions indicative of the current being zero, measure a zero current voltage and further derive the battery current based on the zero current voltage.

15. A method comprising:

measuring, by a controller, a current from a battery configured to operate at the current in a nominal current range for a time greater than in a maximum current range; and

changing, by the controller, an output voltage, in response to a change in the current, by a greater amount when the current is in the nominal current range than when the current is in the maximum current range.

16. The method of claim 15 wherein the output voltage is defined by an exponential function of the current.

17. The method of claim 15 wherein the output voltage is defined by a piecewise linear function of the current.

18. The method of claim 15 wherein the output voltage is defined such that a ratio between a change in the output voltage and the change in the current decreases as a magnitude of the current increases.

19. The method of claim 15 wherein the output voltage is defined such that a resolution of the current as represented by the output voltage is greater in the nominal current range than in the maximum current range.

20. The method of claim 15 further comprising:

receiving, by a second controller, the output voltage; and

operating, by the second controller, the battery according to a battery current derived from the output voltage.