Battery capacity estimating system and method

• US 5,404,106 A
• Filed: 04/28/1994
• Issued: 04/04/1995
• Est. Priority Date: 05/26/1993
• Status: Expired due to Term

• Current Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Original Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Inventors: Matsuda, Kazuhiko
• Primary Examiner(s): Regan, Maura K.
• Application Number:
  US08/234,111
• Time in Patent Office: 341 Days
• Field of Search: 320/48, 340/636, 364/481, 364/483, 324/427, 324/429, 324/430, 324/431, 324/433
• US Class Current: 324/431
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• 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
• CPC Class Codes: G01R 31/386 using test-loads
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]

Abstract

A remaining capacity estimating system and method for an automobile battery capable of estimating and displaying an accurate remaining battery capacity by calculating an internal resistance value of the battery based on a terminal voltage in a disconnected state to electrical loads, a terminal voltage in a selectively connected state to an electrical load and a discharge current value in this connected state, then obtaining a remaining battery capacity at the present temperature condition from a map showing a relationship among a remaining battery capacity, a discharge current and an internal resistance, and finally transforming the obtained remaining battery capacity into a remaining battery capacity at a standard temperature condition.

Claims

1. A remaining capacity measuring system for a rechargeable storage battery of an automobile, comprising:

first switching means responsive to a command signal from an electronic control unit for setting said battery in a disconnected state to all of electrical loads of said automobile except said electronic control unit;

second switching means responsive to another command signal from said electronic control unit for setting said battery in a selectively connected state to an electrical load excluding said electronic control unit;

first voltage detecting means for detecting a first voltage between a positive and negative terminal of said battery in said disconnected state;

second voltage detecting means for detecting a second voltage between a positive and negative terminal of said battery in said selectively connected state;

discharge current detecting means for detecting a discharge current flowing between said battery and said electrical load in said selectively connected state;

temperature sensing means for sensing an electrolyte temperature of said battery;

input signal converting means for converting analogue signals of said first voltage signal, said second voltage signal, said discharge current signal and said electrolyte temperature signal, into digital signals and for outputting said digital signals to a CPU of said electronic control unit;

internal resistance calculating means for calculating an internal resistance value of said battery based on said first voltage signal from said input signal converting means, said second voltage signal from said input signal converting means and said discharge current signal from said input signal converting means and for outputting said internal resistance value;

capacity data memory means for storing a remaining capacity level of said battery on a first map parameterizing an internal resistance value and a discharge current value;

capacity estimating means for reading said remaining capacity level corresponding to said internal resistance value and said discharge current value on said first map and for outputting said remaining capacity level;

correction coefficients memory means for storing a temperature correction coefficient on a second map parameterizing an electrolyte temperature;

capacity correcting mean for reading said temperature correction coefficient corresponding to said electrolyte temperature from said second map, for correcting said remaining capacity level outputted from said capacity estimating means by said temperature correction coefficient, and for outputting a corrected remaining capacity level; and

display means for displaying said corrected remaining capacity level outputted from said temperature correcting means.

2. The remaining capacity measuring system according to claim 1, wherein

said internal resistance value is obtained by means of dividing a difference between said first voltage value and said second voltage value by said discharge current value.

3. A remaining capacity measuring system for a rechargeable chargeable storage battery of an automobile, comprising:

first switching means responsive to a command signal from an electronic control unit for setting said battery in a disconnected state to all of electrical loads of said automobile except said electronic control unit;

second switching means responsive to another command signal from said electronic control unit for setting said battery in a selectively connected state to a reference resistance whose resistance value is known;

first voltage detecting means for detecting a first voltage value between a positive and negative terminal of said battery in said disconnected state;

second voltage detecting means for detecting a second voltage value between a positive and negative terminal of said battery in said selectively connected state;

temperature sensing means for sensing an electrolyte temperature of said battery;

input signal converting means for converting analogue signals of said first voltage value signal, said second voltage value signal, and said electrolyte temperature signal, into digital signals and for outputting said digital signals to a CPU of said electronic control unit;

discharge current calculating means responsive to said second voltage value signal from said input signal converting means for calculating a discharge current value based on a resistance value of said reference resistance and for outputting said discharge current;

internal resistance calculating means for calculating an internal resistance value of said battery based on said first voltage value from said input signal converting means, said second voltage value signal from said input signal converting means and said discharge current value signal from said discharge current calculating means and for outputting said internal resistance value signal;

capacity data memory means for storing a remaining capacity level of said battery on a first map parameterizing an internal resistance value and an discharge current value;

capacity estimating means for reading said remaining capacity level corresponding to said internal resistance value and said discharge current value on said first map and for outputting said remaining capacity level;

correction coefficients memory means for storing a temperature correction coefficient on a second map parameterizing an electrolyte temperature;

capacity correcting means for reading said temperature correction coefficient corresponding to said electrolyte temperature from said second map, for correcting said remaining capacity level outputted from said capacity estimating means by said temperature correction coefficient, and for outputting a corrected remaining capacity level; and

display means for displaying said corrected remaining capacity level outputted from said temperature correcting means.

4. The remaining capacity measuring system according to claim 3, wherein

said discharge current is obtained by means of dividing said second voltage by said resistance value of said reference resistance.

5. The remaining capacity measuring system according to claim 3, wherein

said internal resistance value is obtained by means of dividing a difference between said first voltage value and said second voltage value by said discharge current value.

6. The remaining capacity measuring system according to claim 3, wherein

said reference resistance is replaced with at least one electrical equipment of said automobile whose resistance value is known.

7. A method of measuring a remaining capacity of battery for an automobile, comprising the steps of:

setting said battery in a disconnected state to all of electrical loads of said automobile except an electronic control unit;

setting said battery in a selectively connected state to an electrical load excluding said electronic control unit;

detecting a first voltage between a positive and negative terminal of said battery in said disconnected state;

detecting a second voltage between a positive and negative terminal of said battery in said selectively connected state;

detecting a discharge current flowing between said battery and said electrical load in said selectively connected state;

sensing an electrolyte temperature of said battery;

converting analogue signals of said first voltage signal, said second voltage signal, said discharge current signal and said electrolyte temperature signal, into digital signals and outputting said digital signals to a CPU of said electronic control unit;

calculating an internal resistance value of said battery based on said first voltage signal, said second voltage signal and said discharge current signal and outputting said internal resistance value;

storing a remaining capacity level of said battery on a first map parameterizing an internal resistance value and a discharge current value;

reading said remaining capacity level corresponding to said internal resistance value and said discharge current value on said first map and outputting said remaining capacity level;

storing a temperature correction coefficient on a second map parameterizing an electrolyte temperature;

reading said temperature correction coefficient corresponding to said electrolyte temperature on said second map, correcting said remaining capacity by said temperature correction coefficient and outputting a corrected remaining capacity level; and

displaying said corrected remaining capacity level.

8. The method according to claim 7, wherein

said internal resistance value is obtained by means of dividing a difference between said first voltage value and said second voltage value by said discharge current value.

9. A method of measuring a remaining capacity of a battery for an automobile, comprising the steps of:

setting said battery in a disconnected state to all of electrical loads of said automobile except said electronic control unit;

setting said battery in a selectively connected state to a reference resistance whose resistance value is known;

detecting a first voltage value between a positive and negative terminal of said battery in said disconnected state;

detecting a second voltage value between a positive and negative terminal of said battery in said selectively connected state;

sensing an electrolyte temperature of said battery;

converting analogue signals of said first voltage value signal, said second voltage value signal, and said electrolyte temperature signal, into digital signals and outputting said digital signals to a CPU of said electronic control unit;

calculating a discharge current value based on said second voltage value and a resistance value of said reference resistance;

calculating an internal resistance value of said battery based on said first voltage value, said second voltage value and said discharge current value and outputting said internal resistance value signal;

storing a remaining capacity level of said battery on a first map parameterizing an internal resistance value and an discharge current value;

reading said remaining capacity level corresponding to said internal resistance value and said discharge current value on said first map and outputting said remaining capacity level;

storing a temperature correction coefficient on a second map parameterizing an electrolyte temperature;

reading said temperature correction coefficient corresponding to said electrolyte temperature on said second map, correcting said remaining capacity level by said temperature correction coefficient, and outputting a corrected remaining capacity level; and

displaying said corrected remaining capacity level.

10. The method according to claim 9, wherein

said discharge current is obtained by means of dividing said second voltage by said resistance value of said reference resistance.

11. The method according to claim 9, wherein

said internal resistance value is obtained by means of dividing a difference between said first voltage value and said second voltage value by said discharge current value.

12. The method according to claim 9, wherein

said reference resistance is replaced with at least one electrical equipment of said automobile whose resistance value is known.