Battery status detecting method and battery status detecting apparatus

• US 8,378,638 B2
• Filed: 04/16/2008
• Issued: 02/19/2013
• Est. Priority Date: 07/30/2007
• Status: Active Grant

• Current Assignee: Mitsumi Electric Co., Ltd. (MinebeaMitsumi Inc.)
• Original Assignee: Mitsumi Electric Co., Ltd. (MinebeaMitsumi Inc.)
• Inventors: Majima, Yoshihide
• Primary Examiner(s): Tso, Edward
• Assistant Examiner(s): TORRES RUIZ, JOHALI ALEJANDRA
• Application Number:
  US12/081,438
• Publication Number:
  US 20090033292A1
• Time in Patent Office: 1,770 Days
• Field of Search: 320/153
• US Class Current: 320/153
• CPC Class Codes: G01R 31/374 with means for correcting the measurement for temperature or ageing
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements

Abstract

A battery status detecting method for detecting a battery status of a secondary battery is disclosed. The method includes: an open circuit voltage correcting step of obtaining a temperature-corrected value of the open circuit voltage of the secondary battery according to the temperature of the secondary battery, based on first open circuit voltage characteristics indicating the relationship between the open circuit voltage and the temperature of the secondary battery; and a charge rate correcting step of obtaining a temperature-corrected value of the charge rate of the secondary battery according to the temperature-corrected value of the open circuit voltage obtained in the open circuit voltage correcting step, based on second open circuit voltage characteristics indicating the relationship between the open circuit voltage and the charge rate of the secondary battery.

Claims

1. A battery status detecting method for detecting a battery status of a secondary battery, the method comprising:

an open circuit voltage measuring step of measuring an open circuit voltage of the secondary battery by a voltage detecting unit using an output value of a temperature-dependent circuit unit;

a charge rate calculating step of calculating a charge rate of the secondary battery based on charge rate characteristics indicating a relationship between the open circuit voltage and the charge rate of the secondary battery;

an open circuit voltage correcting step of obtaining a temperature-corrected value of the open circuit voltage of the secondary battery according to a temperature of the secondary battery, based on first temperature characteristics indicating a relationship between the open circuit voltage and the temperature of the secondary battery;

a charge rate correcting step of obtaining a temperature-corrected value of the charge rate of the secondary battery according to the temperature-corrected value of the open circuit voltage obtained in the open circuit voltage correcting step, based on the charge rate characteristics indicating the relationship between the open circuit voltage and the charge rate of the secondary battery; and

a measured voltage correcting step of obtaining a temperature-corrected value of the measured open circuit voltage by correcting the measured open circuit voltage according to the temperature of the secondary battery based on second temperature characteristics of the temperature-dependent circuit unit indicating a relationship between input/output temperature characteristics of the temperature-dependent circuit unit and the temperature of the secondary battery,

wherein the second temperature characteristics of the temperature-dependent circuit unit are represented by an approximated curve of a quadratic function formula of an output value of the temperature-dependent circuit unit, the quadratic function formula including the temperature as a variable and the output value of the temperature-dependent circuit unit as a quadratic function of the variable, and

computing the temperature-corrected value of the measured open circuit voltage, at the measured voltage correcting step, based the temperature of the secondary battery and predetermined values of coefficients included in the quadratic function formula.

2. The battery status detecting method as claimed in claim 1, further comprising:

a temperature measuring step of measuring a temperature of the secondary battery by a temperature detecting unit via the temperature-dependent circuit unit.

3. The battery status detecting method as claimed in claim 1, wherein:

the open circuit voltage correcting step includes correcting the measured open circuit voltage according to the temperature of the secondary battery based on the second temperature characteristics.

4. The battery status detecting method as claimed in claim 2, wherein:

the open circuit voltage correcting step includes correcting the measured open circuit voltage according to the temperature measured in the temperature measuring step, based on the second temperature characteristics.

5. A battery status detecting apparatus that detects a battery status of a secondary battery, the apparatus comprising:

an open circuit voltage measuring unit to measure an open circuit voltage of the secondary battery by a voltage detecting unit using an output value of a temperature dependent circuit unit;

a charge rate calculating unit to calculate a charge rate of the secondary battery based on charge rate characteristics indicating a relationship between the open circuit voltage and the charge rate of the secondary battery; and

a correction unit to obtain a temperature-corrected value of the open circuit voltage of the secondary battery according to a temperature of the secondary battery based on first temperature characteristics indicating a relationship between the open circuit voltage and the temperature of the secondary battery, and to obtain a temperature-corrected value of the charge rate of the secondary battery according to the temperature-corrected value of the open circuit voltage based on the charge rate characteristics indicating the relationship between the open circuit voltage and the charge rate of the secondary battery,

wherein the correction unit is further configured to obtain a temperature-corrected value of the measured open circuit voltage of the secondary battery by correcting the measured open circuit voltage according to the temperature of the secondary battery, based on second temperature characteristics of the temperature-dependent circuit unit indicating a relationship between input/output temperature characteristics of the temperature-dependent circuit unit and the temperature of the secondary battery,

wherein the second temperature characteristics of the temperature-dependent circuit unit are represented by an approximated curve of a quadratic function formula of an output value of the temperature-dependent circuit unit, the quadratic function formula including the temperature as a variable and the output value of the temperature-dependent circuit unit as a quadratic function of the variable, and

the correction unit is configured to compute the temperature-corrected value of the measured open circuit voltage based the temperature of the secondary battery and predetermined values of coefficients included in the quadratic function formula.

6. The battery status detecting apparatus as claimed in claim 5, further comprising:

a temperature measuring unit to measure a temperature of the secondary battery by using the temperature-dependent circuit unit.

7. The battery status detecting apparatus as claimed in claim 6, comprising:

an integrated circuit that integrates the open circuit voltage measuring unit and the temperature measuring unit.