Battery capacity detection system with temperature correction

• US 6,275,008 B1
• Filed: 07/03/2000
• Issued: 08/14/2001
• Est. Priority Date: 07/02/1999
• Status: Expired due to Fees

• Current Assignee: Yazaki Corporation
• Original Assignee: Yazaki Corporation
• Inventors: Arai, Youichi, Kamohara, Hideaki, Saigo, Tsutomu
• Primary Examiner(s): Tso, Edward H.
• Time in patent office: 407 Days
• Field of Search: 320/132, 320/150, 320/152, 320/162, 320/164, 320/DIG.21
• US Class Current: 320/132
• CPC Class Codes: G01R 31/006 on road vehicles, e.g. automobiles or trucks testing of ignition installations peculiar to internal combustion engines F02P17/00
• CPC Class Codes: G01R 31/3647 for determining the ability of a battery to perform a critical function, e.g. cranking
• 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 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements

Abstract

A battery capacity detection system according to the invention is provided with: a temperature sensor for sensing a temperature of the battery; a full-charge voltage calculation section for calculating a voltage of the battery in a full charge state by using the temperature sensed by the temperature sensor; and an SOC calculation section for calculating an SOC of the battery by using the voltage of the battery in the full charge state calculated by using the temperature in the full-charge voltage calculation processing section.

Claims

1. A battery capacity detection system comprising:

a temperature sensor sensing a temperature of a battery;

a full-charge voltage calculation processing section for calculating a voltage of the battery in a fully charged state by using the temperature of the battery sensed by the temperature sensor; and

an SOC calculation section for calculating an SOC of the battery by using the voltage of the battery in the full charge state calculated by using the temperature by the full-charge voltage calculation section.

2. An apparatus according to claim 1, further comprising:

a voltage sensor sensing a voltage of the battery;

a current sensor sensing a current flowing from the battery to a load connected to the battery; and

a battery voltage estimation section calculating an estimated voltage of the battery by estimating a voltage of the battery from both an approximation line obtained on the basis of the current and the voltage and a reference current,

wherein the SOC calculation section calculates the SOC of the battery by further using the estimated voltage calculated by the battery voltage estimation section.

3. An apparatus according to claim 2, wherein the battery voltage estimation section collects a predetermined number of values of each of the current and the voltage, and obtains averaged data by respectively averaging the predetermined number of values,

and wherein when a predetermined number of the averaged data is respectively collected and also the averaged data show a strong correlation, the battery voltage estimation section obtains an approximation line of the averaged data, and calculates the estimated voltage from the approximation line and the reference current.

4. An apparatus according to claim 3, wherein the SOC calculation section further calculates the SOC of the battery by further using a discharge end voltage of the battery.

5. An apparatus according to claim 1, further comprising a chargeable capacity calculation section calculating a chargeable capacity of the battery in accordance with a difference between the present SOC of the battery and the SOC of the battery calculated by using the voltage of the battery in the full charge state calculated by using the temperature.

6. An apparatus according to claim 5, wherein a load connected to the battery includes a motor and, when there is an allowance in the chargeable capacity, the battery is charged with a power from the motor.

7. An apparatus according to claim 1, further comprising a data collecting section sampling the voltage sensed by the voltage sensor and the current sensed by the current sensor for sampling time in which a voltage drop caused by polarization of the battery can be ignored.