Systems and methods for state of charge estimation

• US 9,651,624 B2
• Filed: 03/13/2013
• Issued: 05/16/2017
• Est. Priority Date: 12/17/2012
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Gopalakrishnan, Krishnakumar, Mikuteit, Eric I
• Primary Examiner(s): Bui, Bryan
• Application Number:
  US13/800,366
• Publication Number:
  US 20140172333A1
• Time in Patent Office: 1,525 Days
• Field of Search: 702 63
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements

Abstract

The present disclosure includes systems and methods for state of charge estimation. In one embodiment, the present disclosure includes a method comprising receiving a voltage corresponding to a state of charge of a battery, converting the voltage to an estimated state of charge using different algorithms across different ranges. In another embodiment, an offset state of charge is applied to a first state of charge to produce an estimated state of charge.

Claims

1. A method comprising:

receiving a voltage from a battery;

converting the voltage to a first state of charge; and

converting the voltage to an estimated state of charge using a first algorithm when the first state of charge of the battery is in a first range and converting the voltage to said estimated state of charge using a second algorithm when the first state of charge of the battery is in a second range,

wherein converting the voltage to said estimated state of charge using the second algorithm comprises;

accessing a stored state of charge associated with the voltage;

determining if the battery is in a charging state or a discharging state; and

applying an offset state of charge to the stored state of charge when the battery is in one of the charging state or discharging state to produce said estimated state of charge.

2. The method of claim 1 wherein, when the battery is in a charging state, the second algorithm applies the offset state of charge to the stored state of charge, and when the battery is in a discharge state, the second algorithm does not apply the offset state of charge.

3. The method of claim 1 wherein, when the battery is in a discharging state, the second algorithm applies the offset state of charge to the stored state of charge, and when the battery is in a charge state, the second algorithm does not apply the offset state of charge.

4. The method of claim 1 wherein said accessing comprises a table lookup.

5. The method of claim 1 further comprising receiving a temperature from the battery, wherein the first range and the second range are different at different temperatures.

6. The method of claim 1 further comprising receiving a temperature of the battery, wherein the second algorithm further comprises calculating the offset state of charge based on a temperature of the battery, a second state of charge, and a charging state.

7. The method of claim 1 wherein the second algorithm further comprises determining the offset state of charge using a model based on a second state of charge.

8. The method of claim 7 wherein the model is further based on temperature.

9. The method of claim 1 wherein the second algorithm models a difference between a charge curve and a discharge curve across the second range using a polynomial.

10. The method of claim 1 wherein the voltage is an open circuit voltage of the battery.

11. The method of claim 1 wherein the second range begins at a first threshold SOC value, and wherein the second range increases as the temperature increases.

12. A method comprising:

receiving a voltage from a battery;

converting the voltage to a first state of charge;

receiving a temperature from the battery;

determining a threshold using the temperature; and

converting the voltage to an estimated state of charge using a first algorithm when the first state of charge of the battery is in a first range and converting the voltage to said estimated state of charge using a second algorithm when the first state of charge of the battery is in a second range,

wherein the first range and the second range are different at different temperatures, wherein the first range comprises state of charge values below said threshold and the second range comprises state of charge values above said threshold.

13. The method of claim 12 wherein said determining comprises a linear mapping from the temperature to said threshold.

14. A method comprising:

receiving a voltage from a battery;

converting the voltage to a first state of charge; and

converting the voltage to an estimated state of charge using a first algorithm when the first state of charge of the battery is in a first range and converting the voltage to said estimated state of charge using a second algorithm when the first state of charge of the battery is in a second range,

wherein the first range comprises state of charge values below a first threshold, the second range comprises state of charge values above the first threshold and below a second threshold, and a third range comprises state of charge values above the second threshold.

15. The method of claim 14 further comprising converting the voltage from the battery to said estimated state of charge using the first algorithm when the state of charge of the battery is in the third range.

16. A method comprising:

receiving a voltage from a battery;

converting the voltage to a first state of charge; and

converting the voltage to an estimated state of charge using a first algorithm when the first state of charge of the battery is in a first range and converting the voltage to said estimated state of charge using a second algorithm when the first state of charge of the battery is in a second range,

wherein the second algorithm comprises determining an offset state of charge using a model based on a second state of charge,

wherein the model is further based on temperature, and

wherein the model is a polynomial function of the second state of charge and temperature, and wherein the second range is greater than a threshold state of charge.

17. An electronic device comprising:

a battery;

a voltage detection circuit to detect a voltage corresponding to a state of charge of the battery; and

a processing circuit, the processing circuit configured to receive the voltage from the battery, convert the voltage to a first state of charge, and convert the voltage to an estimated state of charge using a first algorithm when the first state of charge of the battery is in a first range and convert the voltage to said estimated state of charge using a second algorithm when the first state of charge of the battery is in a second range,

wherein converting the voltage to said estimated state of charge using the second algorithm comprises;

accessing a stored state of charge associated with the voltage;

determining if the battery is in a charging state or a discharging state; and

applying an offset state of charge to the stored state of charge when the battery is in one of the charging state or discharging state to produce said estimated state of charge.

18. A non-transitory computer readable storage medium having stored thereon computer software executable by a processor, the computer software embodying a method comprising:

receiving a voltage from a battery;

converting the voltage to a first state of charge; and

converting the voltage to an estimated state of charge using a first algorithm when the first state of charge of the battery is in a first range and converting the voltage to said estimated state of charge using a second algorithm when the first state of charge of the battery is in a second range,

wherein converting the voltage to said estimated state of charge using the second algorithm comprises;

accessing a stored state of charge associated with the voltage;

determining if the battery is in a charging state or a discharging state; and

applying an offset state of charge to the stored state of charge when the battery is in one of the charging state or discharging state to produce said estimated state of charge.