FAST CHARGING OF BATTERY USING ADJUSTABLE VOLTAGE CONTROL

• US 20110012563A1
• Filed: 07/17/2009
• Published: 01/20/2011
• Est. Priority Date: 07/17/2009
• Status: Active Grant

• Current Assignee: Tesla Inc.
• Original Assignee: Tesla Motors Incorporated (Tesla Inc.)
• Inventors: Kohn, Scott I., Mehta, Vineet H., Kishiyama, Clay H., Paryani, Anil
• Granted Patent: US 8,754,614 B2
• Time in Patent Office: Days
• US Class Current: 320/162
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 10/443 in response to temperature
• CPC Class Codes: H02J 2310/48 for electric vehicles [EV] or hybrid vehicles [HEV]
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/007184 in response to battery voltage gradient
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A battery cell charger for rapidly charging a lithium ion battery cell (or string of series-parallel connected cells) having a maximum battery cell voltage the battery cell charging system including: a circuit for charging the battery cell using an adjustable voltage charging-profile to apply a charging voltage and a charging current to the battery cell wherein the adjustable voltage charging-profile includes: a first charging stage with a constant first stage charging current and an increasing battery cell voltage with the first stage charging current provided until the first stage charging voltage is about equal to a first stage complete voltage less than the maximum battery cell voltage; one or more intermediate charging stages, each intermediate stage selected from the group consisting of one or more of an intermediate constant voltage stage that provides a decreasing charging current, an intermediate constant current stage that produces an increasing battery cell voltage, and combinations thereof; and a final charging stage with a constant final stage charging voltage about equal to an intermediate stage complete voltage and a decreasing final stage charging current with the final stage charging voltage provided until the final stage charging current reaches a desired charge complete level.

Claims

1. A battery cell charging system, including a charger and a controller, for rapidly charging a lithium ion battery cell, the battery cell charging system comprising:

a circuit for charging the battery cell using an adjustable voltage charging-profile to apply a charging voltage and a charging current to the battery cell wherein said adjustable voltage charging-profile includes;

a first charging stage with a constant first stage charging current and an increasing battery cell voltage with said first stage charging current provided until said first stage charging voltage is about equal to a first stage complete voltage less than a maximum battery cell voltage;

one or more intermediate charging stages, each intermediate stage selected from the group consisting of one or more of an intermediate constant current stage that produces an increasing battery cell voltage, an intermediate constant power stage that produces an increasing battery cell voltage, and an intermediate constant voltage stage that provides a decreasing charging current, and combinations thereof; and

a final charging stage with a constant final stage charging voltage about equal to an intermediate stage complete voltage and a decreasing final stage charging current with said final stage charging voltage provided until said final stage charging current reaches a desired charge complete level.

2. A battery cell charging system for rapidly charging a lithium ion battery cell, the battery cell charging system comprising:

a circuit for charging the battery cell using a variable charge-profile to apply a charging voltage and a charging current to the battery cell wherein said charge-profile is determined responsive to an imaginary R_Bad resistance included in series with an R_Nominal resistance of a DC model for the battery cell wherein said R_Bad includes a function component responsive to one or more of said R_Nominal, a state-of-charge (SOC) of the battery cell, and a temperature of the battery cell such that V_cell is about equal to a maximum battery cell voltage minus charging current times R_Bad.

3. The battery cell charging system of claim 2 wherein said R_Bad includes a component that is about equal to k1 times R_Nominal minus k2 times SOC wherein k1 is about between 0 and 1 and wherein k2 is about 0.001/SOC %.

4. The battery cell charging system of claim 3 wherein said k1 is about equal to 0.1.

5. The battery cell charging system of claim 2 wherein said R_Nominal is determined from a lookup table responsive to cell temperature, age, and SOC.

6. The battery cell charging system of claim 2 wherein said R_Nominal is estimated in real-time or over time.

7. The battery cell charging system of claim 2 wherein said R_Bad is determined from a lookup table responsive to cell temperature, age, and SOC.

8. The battery cell charging system of claim 2 wherein said R_Bad is estimated in real-time or over time.

9. A battery cell charging method for rapidly charging a lithium ion battery cell, the battery cell charging method comprising:

(a) applying, to the battery cell, a constant first stage charging current and an increasing battery cell voltage with said first stage charging current provided until said first stage charging voltage is about equal to a first stage complete voltage less than a maximum battery cell voltage; and

thereafter

(b) applying, to the battery cell, one or more intermediate charging profiles, each intermediate charging profile selected from the group consisting of one or more of an intermediate constant current stage that produces an increasing battery cell voltage, an intermediate constant power stage that produces an increasing battery cell voltage, an intermediate constant voltage stage that provides a decreasing charging current, and combinations thereof; and

thereafter

(c) applying, to the battery cell, a constant final stage charging voltage about equal to an intermediate stage complete voltage and a decreasing final stage charging current with said final stage charging voltage provided until said final stage charging current reaches a desired charge complete level.

10. A battery cell charging method for rapidly charging a lithium ion battery cell, the battery cell charging method comprising:

(a) applying, responsive to a charge-profile, a varying charging voltage and a varying charging current to the battery cell wherein said charge-profile is determined responsive to an imaginary R_Bad resistance included in series with an R_Nominal resistance of a DC model for the battery cell wherein said R_Bad includes a function component responsive to one or more of said R_Nominal, a state-of-charge (SOC) of the battery cell, and a temperature of the battery cell such that V_cell is about equal to a maximum battery cell voltage minus charging current times R_Bad.

11. The battery cell charging method of claim 10 wherein said R_Bad includes a component about equal to k1 times R_Nominal minus k2 times SOC wherein k1 is about between 0 and 1 and wherein k2 is about 0.001/SOC %.

12. The battery cell charging method of claim 10 wherein said k1 is about equal to 0.1.

13. The battery cell charging method of claim 10 wherein said R_Nominal is determined from a lookup table responsive to cell temperature, age, and SOC.

14. The battery cell charging method of claim 10 wherein said R_Nominal is estimated in real-time or over time.

15. The battery cell charging method of claim 10 wherein said R_Bad is determined from a lookup table responsive to cell temperature, age, and SOC.

16. The battery cell charging method of claim 10 wherein said R_Bad is estimated in real-time or over time.

17. A battery cell charging system, including a charger and a controller, for rapidly charging a lithium ion battery cell, the battery cell charging system comprising:

a circuit for charging the battery cell using an adjustable voltage charging-profile to apply a charging voltage and a charging current to the battery cell wherein said adjustable voltage charging-profile includes;

a first charging stage with a constant first stage charging power and an increasing battery cell voltage with said first stage charging power provided until said first stage charging voltage is about equal to a first stage complete voltage less than a maximum battery cell voltage;

one or more intermediate charging stages, each intermediate stage selected from the group consisting of one or more of an intermediate constant current stage that produces an increasing battery cell voltage, an intermediate constant power stage that produces an increasing battery cell voltage, and an intermediate constant voltage stage that provides a decreasing charging current, and combinations thereof; and

a final charging stage with a constant final stage charging voltage about equal to an intermediate stage complete voltage and a decreasing final stage charging current with said final stage charging voltage provided until said final stage charging current reaches a desired charge complete level.

18. A battery cell charging method for rapidly charging a lithium ion battery cell, the battery cell charging method comprising:

(a) applying, to the battery cell, a constant first stage charging power and an increasing battery cell voltage with said first stage charging power provided until said first stage charging voltage is about equal to a first stage complete voltage less than a maximum battery cell voltage; and

thereafter

(b) applying, to the battery cell, one or more intermediate charging profiles, each intermediate charging profile selected from the group consisting of one or more of an intermediate constant current stage that produces an increasing battery cell voltage, an intermediate constant power stage that produces an increasing battery cell voltage, an intermediate constant voltage stage that provides a decreasing charging current, and combinations thereof; and

thereafter

(c) applying, to the battery cell, a constant final stage charging voltage about equal to an intermediate stage complete voltage and a decreasing final stage charging current with said final stage charging voltage provided until said final stage charging current reaches a desired charge complete level.