Vehicle battery's open circuit voltage estimating method and a system therefor

• US 6,531,875 B2
• Filed: 12/05/2001
• Issued: 03/11/2003
• Est. Priority Date: 12/08/2000
• Status: Expired due to Fees

• Current Assignee: Yazaki Corporation
• Original Assignee: Yazaki Corporation
• Inventors: Satake, Shuji
• Primary Examiner(s): TOATLEY, GREGORY J
• Application Number:
  US10/002,114
• Publication Number:
  US 20020113594A1
• Time in Patent Office: 461 Days
• Field of Search: 324/427, 324/429, 324/134, 324/162
• US Class Current: 324/429
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/388 involving voltage measurements

Abstract

A vehicle battery'"'"'s open circuit voltage estimating method and a system therefor for relatively correctly estimating an open circuit voltage of a battery on a vehicle within a relatively short period after completion of the charge or the discharge also without a temperature correction is provided. A disconnected voltage measuring means 23a-1 measures a disconnected voltage of the battery multiple times in a definite period of time after a predetermined period of time after completion of charge or discharge of the battery. An approximate expression determining means 23a-2 determines a power approximate expression having a negative power number by using a difference value of the measured disconnected voltage and an assumed open circuit voltage. And, an arithmetic operation controlling means 23a-3 makes the approximate expression determining means update the assumed open circuit voltage and determine the power approximate expression repeatedly until the power number of the determined power approximate expression becomes −0.5 or about −0.5, and the assumed open circuit voltage is estimated to be the open circuit voltage when the power number becomes −0.5 or about −0.5.

Claims

1. A vehicle battery'"'"'s open circuit voltage estimating method for estimating an open circuit voltage of a vehicle-borne battery supplying electric power to vehicle-borne loads, comprising the steps of:

measuring a disconnected voltage of the battery multiple times in a definite period of time after a predetermined period of time after completion of charge or discharge of the battery;

determining a power approximate expression having a negative power number by using a difference value of the measured disconnected voltage and an assumed open circuit voltage;

repeating the determination of the power approximate expression by updating the assumed open circuit voltage until the power number of the determined power approximate expression becomes −

0.5 or about −

0.5; and

estimating the assumed open circuit voltage to be the open circuit voltage when the power number becomes −

0.5 or about −

0.5.

2. The vehicle battery'"'"'s open circuit voltage estimating method as set forth in claim 1, wherein

the power approximate expression is given by α ·

t^D with time t, an unknown coefficient α

, and an unknown negative power number D, when the disconnected voltage is measured after completion of the charge.

3. The vehicle battery'"'"'s open circuit voltage estimating method as set forth in claim 1, wherein

the difference value for determining the power approximate expression is an absolute value obtained by subtracting the assumed open circuit voltage from the measured disconnected voltage when the disconnected voltage is measured after completion of the discharge, and

the power approximate expression is given by α

·

t^D with time t, an unknown coefficient α

, and an unknown negative power number D.

4. The vehicle battery'"'"'s open circuit voltage estimating method as set forth in claim 2 or claim 3, wherein

the power number D of the power approximate expression is determined by a regression computation processing by using a plurality of measured disconnected voltages and corresponding times from the completion of the charge or the discharge.

5. A vehicle battery'"'"'s open circuit voltage estimating system for estimating an open circuit voltage of a vehicle-borne battery supplying electric power to vehicle-borne loads, comprising:

a disconnected voltage measuring means for measuring a disconnected voltage of the battery multiple times in a definite period of time after a predetermined period of time after completion of charge or discharge of the battery;

an approximate expression determining means for determining a power approximate expression having a negative power number by using a difference value of the measured disconnected voltage and an assumed open circuit voltage; and

an arithmetic operation controlling means for making the approximate expression determining means update the assumed open circuit voltage and determine the power approximate expression repeatedly until the power number of the determined power approximate expression becomes −

0.5 or about −

0.5,

wherein the assumed open circuit voltage is estimated to be the open circuit voltage when the power number becomes −

0.5 or about −

0.5.

6. The vehicle battery'"'"'s open circuit voltage estimating system as set forth in claim 5, wherein

the power approximate expression is given by α ·

t^D with time t, an unknown coefficient α

, and an unknown negative power number D, when the disconnected voltage is measured after completion of the charge.

7. The vehicle battery'"'"'s open circuit voltage estimating system as set forth in claim 5, wherein

the difference value for determining the power approximate expression is an absolute value obtained by subtracting the assumed open circuit voltage from the measured disconnected voltage when the disconnected voltage is measured after completion of the discharge, and

the power approximate expression is given by α

·

t^D with time t, an unknown coefficient α

, and an unknown negative power number D.

8. The vehicle battery'"'"'s open circuit voltage estimating system as set forth in claim 6 or claim 7, wherein

the power number D of the power approximate expression is determined by a regression computation processing by using a plurality of measured disconnected voltages and corresponding times from the completion of the charge or the discharge.