METHOD FOR DETERMINING BATTERY STATE OF CHARGE THAT ACCOUNTS FOR CURRENT MEASUREMENT NOISE AND CALIBRATION DRIFT
Publication Date: 2014-Mar-28
The IP.com Prior Art Database
The present invention discloses a technique in which current measurement noise and calibration drift are considered to improve an accuracy of SOC calculation. Current measurement noise is considered by introducing a variable window around a current measurement zero point. Calibration drift is considered by taking a measured battery current flow when the battery is open circuited. Such correction factor is added to all battery current readings when the battery is connected to a load.
The present invention relates generally to a battery, and more particularly to a state of charge (SOC) of the battery.
Generally, current state of charge (SOC) of a battery, which is expressed in percentage, is measured by starting at a known SOC and measuring the charge added and removed over time. Measurement of the charge added and removed over time is performed by measuring an electric current. Such electrical current flows into and out of the battery over time. Measurement of electrical current over time is calculated in terms of Ampere-Hours (AH). Such measurement is compared with a capacity of the battery in AH to determine the current SOC. Current SOC is an addition of the starting SOC and a change in SOC.
However, conventional techniques do not improve accuracy of the SOC calculation.
Therefore, there is a need in the art for a technique to improve accuracy of SOC calculation.
The present invention discloses a technique in which current measurement noise and calibration drift are considered to improve accuracy of SOC calculation.
Current measurement noise is considered by introducing a variable window around a measurement zero point. The current measurement zero point extends from minus X ampere to plus X ampere. Any current within the variable window is not counted in SOC calculation. Calibration drift is considered by t...