TIME-BASED VEHICLE BATTERY BALANCING SYSTEM AND METHOD

• US 20140159672A1
• Filed: 02/18/2014
• Published: 06/12/2014
• Est. Priority Date: 07/28/2011
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Blakemore, Bruce Carvell, Gale, Allan Roy, Elie, Larry Dean
• Granted Patent: US 8,868,279 B2
• Time in Patent Office: Days
• US Class Current: 320/134
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/80 Time limits
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 53/14 Conductive energy transfer
• CPC Class Codes: B60L 58/15 Preventing overcharging
• CPC Class Codes: B60L 58/22 Balancing the charge of battery modules
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• 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 90/14 Plug-in electric vehicles

Abstract

A power system for a vehicle may include at least one controller and a battery having a plurality of cells. The at least one controller may, for each of the cells, determine a voltage of the cell, determine a discharge time to reduce the voltage to a value approximately equal to a minimum of the determined voltages, and cause the cell to discharge for the discharge time to balance the battery.

Claims

1. A method of balancing a vehicle battery including a plurality of cells, the method comprising:

for each of the cells,

determining a value of an electrical parameter of the cell,

determining a discharge time to reduce the determined value of the electrical parameter to a target value, and

discharging the cell for the discharge time to balance the vehicle battery.

2. The method of claim 1 wherein determining a value of an electrical parameter of the cell includes measuring the voltage of the cell after the vehicle has been off for a predetermined period of time, the predetermined period of time being based on a polarization charge dissipation rate of the cell.

3. The method of claim 1 wherein determining a value of an electrical parameter of the cell includes periodically measuring the voltage of the cell and averaging the measurements.

4. The method of claim 1 further comprising identifying a minimum of the determined values of the electrical parameter, wherein the target value is the minimum of the determined values.

5. The method of claim 1 further comprising charging the cells.

6. The method of claim 1 wherein the electrical parameter is voltage.

7. A power system for a vehicle comprising:

a battery including a plurality of cells; and

at least one controller configured to, for each of the cells, determine a voltage of the cell, determine a discharge time to reduce the voltage to a value approximately equal to a minimum of the determined voltages, and cause the cell to discharge for the discharge time to balance the battery.

8. The system of claim 7 wherein determining a voltage of the cell includes measuring the voltage of the cell after the vehicle has been shut down for a predetermined period of time, the predetermined period of time being based on a polarization charge dissipation rate of the cell.

9. The system of claim 7 wherein determining a voltage of the cell includes periodically measuring the voltage of the cell and averaging the measurements.

10. The system of claim 7 wherein the at least one controller is further configured to cause the cells to acquire charge after causing the cells to discharge for the discharge times.