University of Twente Student Theses


Integrated state-of-charge circuit for rechargeable batteries

Velner, J. (2008) Integrated state-of-charge circuit for rechargeable batteries.

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Abstract:The aim of this work is to create a low power system that can measure positive and negative voltages varying in magnitude from 100 μV to 100 mV with a relative accuracy of 1% or better. These voltages correspond to a current flow to or from a battery powering a DECT IC. Since these currents are quasi static, no accurate time domain representation is required, as long as the total charge is measured accurately. Since the system is constantly active and battery powered it needs to have a low current consumption. A maximum limit of 100 μA has been specified for this. The final result is a system that is based on converting the input voltage to a current using a differential pair with a low transconductance and continuously integrating this current. When the output voltage of the integrator reaches a certain threshold, a fixed amount of charge is either added to or removed from the integrator. By counting these charge packages one can measure the total charge that was supplied to or taken from the battery. The system will function correctly if the absolute component values vary, but calibration is required if absolute charge values are to be measured.
Item Type:Essay (Master)
SiTel Semiconductor
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:54 computer science
Programme:Computer Science MSc (60300)
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