Capacity Maintenance Rate Estimation Apparatus or Capacity Maintenance Rate Estimation Method

• US 20180335479A1
• Filed: 11/20/2015
• Published: 11/22/2018
• Est. Priority Date: 11/20/2015
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Hashimoto, Hiroaki
• Granted Patent: US 10,634,724 B2
• Time in Patent Office: Days
• CPC Class Codes: G01R 31/36 Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: G01R 31/388 involving voltage measurements
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A capacity ratio estimation apparatus and method for a battery detects current and voltage of the battery; specifies an integration period from a first time point to a second time point and calculates an integration value of the current for the integration period based on detected current; calculates a first open circuit voltage at the first time point based on the detected voltage and calculates a second open circuit voltage of the battery at the second time point based on the detected voltage; and estimates a capacity ratio of the battery based on a voltage difference between the first open circuit voltage and the second open circuit voltage and an integration value satisfying predetermined conditions. The integration value is equal to a predetermined lower limit value or greater and an average value of the current of the battery for the integration period is equal to the predetermined value or greater.

Claims

1. A capacity ratio estimation apparatus for estimating a capacity ratio of a battery, comprising:

a detector for detecting current of the battery and voltage of the battery; and

a controller that;

specifies an integration period from a first time point to a second time point and calculates an integration value of the current of the battery for the integration period based on detected current of the battery detected by the detector, the first time point and the second time point being a time point when an absolute value of the current of the battery is in the vicinity of 0 amperes;

calculates a first open circuit voltage of the battery at the first time point based on the detected voltage and calculating a second open circuit voltage of the battery at the second time point based on the detected voltage; and

estimates a capacity ratio of the battery based on a voltage difference between the first open circuit voltage and the second open circuit voltage, and the integration value that satisfies predetermined conditions,

wherein the predetermined conditions include that the integration value is a predetermined lower limit value or greater and a current average value of the battery for the integration period is a predetermined value or greater.

2. The capacity ratio estimation apparatus according to claim 1, wherein the predetermined conditions include that the integration value is within a range of the predetermined lower limit value or greater to a predetermined upper limit value or less.

3. The capacity ratio estimation apparatus according to claim 1, wherein

the detector detects a temperature of the battery, and

the predetermined conditions include that the temperature of the battery is a predetermined threshold value or higher.

4. The capacity ratio estimation apparatus according to claim 1, wherein

the predetermined conditions include that an absolute value of the detected current of the battery is a predetermined current threshold value or greater for a predetermined period of time.

5. The capacity ratio estimation apparatus according to claim 1, wherein

the controller calculates the first open circuit voltage based on the detected voltage of the battery after elapse of a predetermined polarization period from the first time point, and calculates the second open circuit voltage based on the detected voltage of the battery after elapse of a predetermined polarization period from the second time point.

6. The capacity ratio estimation apparatus according to claim 1, wherein

the controller sets the predetermined lower limit value based on an estimated value of the capacity ratio.

7. The capacity ratio estimation apparatus according to claim 1, wherein

the controller sets the predetermined lower limit value based on internal resistance of the battery or a period of use of the battery.

8. A capacity ratio estimation method for estimating a capacity ratio of a battery, comprising:

detecting current of the battery and voltage of the battery using a sensor;

specifying an integration period from a first time point to a second timepoint, the first time point and the second timepoint being a time point when an absolute value of the current of the battery is in the vicinity of 0 amperes;

calculating, based on detected current of the battery detected by the sensor, an integration value of the current of the battery for the integration period;

calculating, based on detected voltage detected by the sensor, a first open circuit voltage of the battery at the first time point;

calculating, based on the detected voltage detected by the sensor, second open circuit voltage of the battery at the second time point;

calculating a voltage difference between the first open circuit voltage and the second open circuit voltage; and

estimating a capacity ratio of the battery based on the integration value satisfying predetermined conditions and the voltage difference, wherein

the predetermined conditions include that the integration value is a predetermined lower limit value or greater, and an average value of the current of the battery in the integration period is a predetermined value or greater.