Battery cell voltage balancing system and method

• US 8,897,940 B2
• Filed: 07/28/2011
• Issued: 11/25/2014
• 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
• Primary Examiner(s): Badii, Behrang
• Assistant Examiner(s): GREENE, DANIEL LAWSON
• Application Number:
  US13/192,510
• Publication Number:
  US 20130030617A1
• Time in Patent Office: 1,216 Days
• Field of Search: 701/22
• US Class Current: 701/22
• 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 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/50 using propulsion power supplied by batteries or fuel cells
• CPC Class Codes: B60L 50/60 using power supplied by batteries in combination with fuel cells B60L50/75
• CPC Class Codes: B60L 53/14 Conductive energy transfer
• CPC Class Codes: B60L 58/22 Balancing the charge of battery modules
• CPC Class Codes: G01R 31/36 Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H02J 2207/40 adapted for charging from various sources, e.g. AC, DC or multivoltage
• CPC Class Codes: H02J 2310/48 for electric vehicles [EV] or hybrid vehicles [HEV]
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/00716 in response to integrated charge or discharge current
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• 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

Abstract

A vehicle may include an electric machine that generates motive power for the vehicle, a plurality of cells that store energy for the electric machine, and at least one controller. The at least one controller may cause the cells to receive current for a period of time and, during the period of time, cause at least some of the cells to supply cell load current such that at the expiration of the period of time, the amount of energy stored by the cells is at least equal to a predetermined target energy level.

Claims

1. A vehicle comprising:

an electric machine configured to generate motive power for the vehicle;

a battery including a plurality of cells configured to store energy for the electric machine; and

at least one controller configured to cause the cells to receive current for a predetermined period of time and, during the predetermined period of time, to cause at least some of the cells to supply cell load current such that at the expiration of the predetermined period of time, the cell voltages are approximately equal to a target voltage and the amount of energy stored by the cells is at least equal to a predetermined target energy level, wherein the predetermined period of time is based on the target voltage.

2. The vehicle of claim 1 wherein the at least one controller is further configured to determine, for each of the at least some of the cells, a duration of time to cause the cell to supply load current.

3. The vehicle of claim 2 wherein the at least one controller is further configured to, for each of the cells, determine an initial capacity of the cell and wherein the duration of time to cause the cell to supply load current is based on the initial capacity of the cell.

4. The vehicle of claim 2 wherein the at least one controller is further configured to determine whether each of the durations of time is less than the predetermined period of time.

5. A method for charging a vehicle battery comprising:

causing cells of the battery to receive current for a predetermined period of time; and

,

during the predetermined period of time, causing at least some of the cells to supply cell load current such that at the expiration of the predetermined period of time, the cell voltages are approximately equal to a target voltage, wherein the predetermined period of time is based on the target voltage.

6. The method of claim 5 wherein the predetermined period of time is further based on a rate at which the cells receive the current.

7. The method of claim 5 wherein at the expiration of the predetermined period of time, the amount of energy stored by the cells is at least equal to a predetermined target energy level.

8. The method of claim 5 further comprising determining, for each of the at least some of the cells, a duration of time to cause the cell to supply cell load current.

9. The method of claim 8 further comprising determining, for each of the cells, an initial capacity in the cell and wherein the duration of time to cause the cell to supply cell load current is based on the initial capacity in the cell.

10. The method of claim 8 further comprising determining whether each of the durations of time is less than the predetermined period of time.

11. A power system comprising:

a battery including a plurality of cells; and

at least one controller configured to cause the cells to acquire charge for a predetermined period of time such that at the expiration of the predetermined period of time, the voltages of the cells are approximately equal to a target voltage, wherein the rate at which charge is acquired by the cells is different among at least some of the cells for at least a determined portion of the predetermined period of time and wherein the predetermined period of time is based on the target voltage.

12. The system of claim 11 wherein at the expiration of the predetermined period of time, the amount of energy stored by the cells is at least equal to a predetermined target energy level.