Indian Journal of Science and Technology

Abstract

Objectives: Batteries have to be charged with constant current when they have very low charge and have to be charged at constant voltage when they have high charge. Methods/Statistical Analysis: To take care of the above mentioned objective a bidirectional battery charger is developed which can work as buck converter to boost converter from one direction to another. The buck operation can be used to charge a low voltage battery from a high voltage source and the boost operation is for vice versa. Findings: A Magnetically Coupled Bidirectional Battery Charger, the low voltage battery and high voltage battery have smooth and stable transition from Constant Current (CC) to Constant Voltage (CV) that can be achieved using neither control loop nor any extra switches. Applications/Improvements: To amplify the dc input voltage to the required high voltage level, an LC-circuit with high quality factor (Q-factor) is employed, in which, to make and break a high current pulse through the inductance, a power switch of MOSFET is employed. Usually, energy is stored in an inductance, when the current is made to flow through the inductance and if this current is cut, then the stored energy in the inductance is transferred to capacitance, which results in a high voltage across the capacitor that is filtered to be used to charge the high voltage batteries.
Keywords: Bidirectional Battery Charger, Buck/Boost Converter, Magnetically Coupled, Quality factor (Q-factor)