Regenerative braking using buckboost converter

Abstract

A Buck Boost converter circuit has been designed and simulated to drive a dc motor for an electric vehicle. The design consists of an IGBT Buck-Boost converter, the battery pack in the Buck side and a capacitor in the Boost side. The main battery has the motor load connected to it. The design helps in improving the efficiency of the DC motor by using the bidirectional buck boost converter along with the battery pack and capacitor.It provides energy to the motor during acceleration and also facilitates the energy regeneration during braking or deceleration. The incorporation of the regenerative braking can improve the efficiency as much as 25% and therefore improve the driving range. During boost operation the converter transfers the energy from the capacitor to the battery(battery gets charged) while during regeneration converter works in buck mode and transfers energy from battery to capacitor(capacitor is charged).There are a number of options for DC DC converter such as Boost,Buck converter, Isolated/Non isolated Half bridge Buck Boost converter,Full Bridge converter and ,Cuk Converter.The isolated converters are preferred as they don’t include transformers and hence increase the overall efficiency of the system along with reduction of size and weight of the system.A controller was designed to generate a controlled PWM signal input to the igbt switches. The battery voltage is measured and an error signal is generated with respect to a reference voltage. This error is given as input to a PI controller and the controller generates a PWM switching pattern by using a comparator. The controller thus controls the amount of energy transferred to the capacitor.In present work the controller is designed and simulated for both the operating modes-Buck mode and Boost mode.