Experimental Characterization of Lithium Polymer Battery Charging Cycles

Experimental Characterization of Lithium Polymer Battery Charging Cycles
during Bilateral Energy Exchange in Power-Autonomous Systems
Pushpak Jha
MAE Department
Lithium polymer batteries are widely used in a variety of applications. However not
much about their battery characteristics such as capacity fade, battery life and cell voltage drop
are well known. Specifically these characteristics are not known when the batteries are cyclically
discharged then recharged with low depth of discharges. An experimentally setup has been
designed to discharge then recharge the battery cyclically using a DC motor, load inertia, some
circuitry and MATLAB/Simulink. The goal of this summer was to have the setup built and
working. The circuitry involved in the setup is used to regulate the torque of the motor by
controlling the current. This means designing the circuit so it can auto-correct in case the actual
current starts to change from the desired current. This is not a simple task. The major issue lies in
being able to accurately measure bi-directional current with a relatively noise-free signal. Once
that is accomplished, a proportional integral (PI) controller can be used to do the auto-correction
needed. Currently we have a circuit that is mostly working but needs to be fine tuned. We hope
to finish building the setup in the near future and then being to gather and analyze the data.
{2011}, {Electrical Engineering}, {Honors}, {Dr. Kevin B. Fite}