ABSTRACT
The intention of the project is to design a battery charger that could intelligently charge several different types of batteries, using PIC control with voltage and temperature feedback from the battery.
The charger is designed to charge AA NiMH, AAA NiCad, Li-Ion batteries with constant voltage and constant current modes, depending on each battery’s physical characteristics and ideal charge profile. Each battery’s charging process is broken up into distinct stages, in which the charge rate and the type of charge are varied. The charger takes 220V AC input that is converted to a constant current or constant voltage DC output.
The device consists of rectifier, filter, and regulator circuits, which will remain unchanged for each different charging process. For each given stage, the PIC will generate a PWM signal based on a calculated duty cycle value, which will then control the level of the voltage and current outputted to the battery by adjusting the duty cycle of the buck converter.