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TECHNIQUE FOR DETERMINING STATE OF CHARGE FOR A BATTERY

IP.com Disclosure Number: IPCOM000191264D
Publication Date: 2009-Dec-24
Document File: 5 page(s) / 19K

Publishing Venue

The IP.com Prior Art Database

Abstract

A technique for determining state of charge for a battery is disclosed. The proposed technique determines the state of charge with enhanced accuracy across wide range, especially at low range of current. In order to ensure desired accuracy, the proposed technique utilizes two current sensors. Further, the present technique also provides a protection circuitry which prevents damage to the sensor when the sensor range is exceeded.

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Page 1 of 5

RP13216

TECHNIQUE FOR DETERMINING STATE OF CHARGE FOR A BATTERY

BRIEF ABSTRACT

    A technique for determining state of charge for a battery is disclosed. The proposed technique determines the state of charge with enhanced accuracy across wide range, especially at low range of current. In order to ensure desired accuracy, the proposed technique utilizes two current sensors. Further, the present technique also provides a protection circuitry which prevents damage to the sensor when the sensor range is exceeded.

KEYWORDS

    Battery, state of charge, SOC, state of discharge, sensor(s), protection circuitry, hybrid vehicles, electric vehicles, zero current, integration error and zero current.

DETAILED DESCRIPTION

    In hybrid and electric vehicles, the batteries play predominant role in terms of system performance and cost. Accurate determination of the amount of charge remaining in the battery is particularly desirable in electric vehicle traction batteries. The available charge is directly related to the range available from the vehicle before a recharge.

    Moreover, the accurate determination of battery state of charge is of significant importance for battery control and monitoring. Expanding the range of the current over which the current sensor takes measurements causes a decrease in the resolution of the sensor, and this causes the computation precision for the state of charge to decrease.

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RP13216

    Due to high dynamic range of the current, the techniques, based on integrating the instantaneous value of the current, are unable to provide accuracy specifically at small current compared with rated current including the region close to zero. For certain applications, the time spent in the proximity of zero current can be significant and hence, the integration error can lead to problems in determining the actual state of charge. Therefore, there is a need in the state of art for a technique that accurately determines the state of charge for the battery across wide range.

    The present technique accurately determines the state of charge for a battery (such as, used in electric vehicle, a hybrid-drive vehicles, and/or the like) even at small currents.

    Figure 1 illus...