Design and implementation of an integrated, non isolated, inverted DC-DC buck-boost converter for battery charging

Abstract

Energy can be transformed from one form to another form and can also be stored. Electrical energy can be generated, distributed and can be stored using batteries. This project describes a method of charging a 12V battery with constant output voltage and variable input voltage using Buck-Boost topology. The variation in duty cycle of MOSFET will provide variation in output voltage. The error in output voltage will decide the extent of variation in duty cycle. Thus the system becomes closed loop. Now-a-days Micro-controllers(MSP430) are used in industries and by researchers for providing high accuracy and frequency. MSP430FXX series has 12-bit ADC which provides precision in measurements of sampling voltages. An isolated driving circuit is used for providing safety to the microcontroller as the transients or the reverse currents can cause damage to the controller. An inverted output voltage is obtained from the buck-boost topology. The demand of current from the MOSFET is the reason for gate driver in the system and the isolation between the controller and the switching MOSFET is provided through optocoupler.