Method For Managing Power Limits For A Battery

• US 20110156657A1
• Filed: 03/09/2011
• Published: 06/30/2011
• Est. Priority Date: 11/10/2010
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Anderson, Richard Dyche
• Granted Patent: US 8,159,188 B2
• Time in Patent Office: Days
• US Class Current: 320/134
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H02J 7/0069 Charging or discharging for charge maintenance, battery initiation or rejuvenation
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A method for managing power limits for a battery includes the step of increasing a minimum operating state of charge after an initial power capability has decreased to the point where a predefined full discharge power is not available at an initial minimum operating state of charge. The increased minimum operating state of charge can be chosen such that the full discharge power is available. The increased minimum state of charge may not be chosen to provide the full discharge power if the increased minimum state of charge is greater than a maximum low limit state of charge.

Claims

1. A method for managing power limits for a battery having a power capability that is a function of at least a state of charge (S.O.C.) of the battery, the battery further having a minimum operating S.O.C. and a discharge power limit that is a function of at least the S.O.C., an initial discharge power limit being set below an initial power capability such that a predefined full discharge power is available at states of charge above an initial minimum operating S.O.C., the method comprising:

determining whether the full discharge power is available at the initial minimum operating S.O.C. after the power capability has decreased from the initial power capability;

reducing the discharge power limit at a first predetermined S.O.C. to a first point below a present power capability curve;

defining a first portion of a discharge power limit curve as containing the first point and generally parallel to the present power capability curve; and

defining a second portion of the discharge power limit curve as having a generally constant power level above a second predetermined S.O.C.

2. The method of claim 1, wherein the first predetermined S.O.C. is the initial minimum operating S.O.C.

3. The method of claim 1, wherein the second predetermined S.O.C. is a present S.O.C. of the battery.

4. The method of claim 1, wherein the initial discharge power limit is defined by an initial discharge power limit curve, and the second predetermined S.O.C. is defined by an intersection of the initial discharge power limit curve and the first portion of the discharge power limit curve at an S.O.C. above the initial minimum operating S.O.C.

5. The method of claim 4, wherein the first portion of the discharge power limit curve further intersects the initial discharge power limit curve at an S.O.C. below the initial minimum operating S.O.C.

6. The method of claim 1, wherein the second portion of the discharge power limit curve has an S.O.C. range above an S.O.C. range of the first portion of the discharge power limit curve.

7. The method of claim 1, wherein the initial discharge power limit is defined by an initial discharge power limit curve, the method further comprising defining a third portion of the discharge power limit curve as coincident with a portion of the initial discharge power limit curve below the initial minimum operating S.O.C.

8. A method for managing power limits for a battery, comprising:

reducing a discharge power limit curve for the battery after a present power capability curve has lowered such that a predefined full discharge power is not available at an initial minimum operating state of charge (S.O.C.),

the reduced discharge power limit curve having a first portion generally parallel to a present power capability curve, and a second portion generally horizontal above a predetermined S.O.C.

9. The method of claim 8, wherein the predetermined S.O.C. is a present S.O.C. of the battery.

10. The method of claim 8, wherein the predetermined S.O.C. is defined by the intersection of the first portion of the reduced discharge power limit curve and an initial discharge power limit curve, the intersection being at an S.O.C. above the initial minimum operating S.O.C.

11. The method of claim 8, wherein the first portion of the reduced discharge power limit curve intersects an initial discharge power limit curve at an S.O.C. below the initial minimum operating S.O.C.

12. The method of claim 8, wherein the reduced discharge power limit curve includes a third portion coincident with an initial discharge power limit curve at an S.O.C. below the initial minimum operating S.O.C.

13. The method of claim 12, wherein the second portion of the reduced discharge power limit curve has an S.O.C. range above the S.O.C range of the first portion of the reduced discharge power limit curve, and the third portion of the reduced discharge power limit curve has an S.O.C. range below the S.O.C. ranges of the first and second portions of the reduced discharge power limit curve.

14-20. -20. (canceled)

21. A vehicle, comprising:

an electric motor operable to propel the vehicle;

a battery operable to provide electric power to the motor and having a power capability that is a function of at least a state of charge (S.O.C.) of the battery, the battery further having a minimum operating S.O.C. and a discharge power limit that is a function of at least the S.O.C., an initial discharge power limit being set below an initial power capability such that a predefined full discharge power is available at states of charge above an initial minimum operating S.O.C.; and

at least one controller configured to execute a control strategy including the steps of;

determining whether the full discharge power is available at the initial minimum operating S.O.C. after the power capability has decreased from the initial power capability,

reducing the discharge power limit at a first predetermined S.O.C. to a first point below a present power capability curve,

defining a first portion of a discharge power limit curve as containing the first point and generally parallel to the present power capability curve, and

defining a second portion of the discharge power limit curve as having a generally constant power level above a second predetermined S.O.C.

22. The vehicle of claim 21, further comprising an engine operatively connected to the motor.

23. The vehicle of claim 21, wherein the first predetermined S.O.C. is the initial minimum operating S.O.C.

24. The vehicle of claim 21, wherein the second predetermined S.O.C. is a present S.O.C. of the battery.

25. The vehicle of claim 21, wherein the initial discharge power limit is defined by an initial discharge power limit curve, and the second predetermined S.O.C. is defined by an intersection of the initial discharge power limit curve and the first portion of the discharge power limit curve at an S.O.C. above the initial minimum operating S.O.C.

26. The vehicle of claim 25, wherein the first portion of the discharge power limit curve further intersects the initial discharge power limit curve at an S.O.C. below the initial minimum operating S.O.C.

27. The vehicle of claim 21, wherein the initial discharge power limit is defined by an initial discharge power limit curve, the control strategy further including the step of defining a third portion of the discharge power limit curve as coincident with a portion of the initial discharge power limit curve below the initial minimum operating S.O.C.