Modeling and Controller Design of a Bidirectional DC-DC Converter for Electric Vehicles System

Abstract

Batteries are the primary energy-storage devices in application of electric vehicles. Battery fed electric drives are commonly being used for electric vehicles applications, due to various advantages, such as: approximately zero emission, definite load leveling, best transient operation and energy recovery during braking operation. To fulfill these requirements converters with bidirectional power flow capabilities are required to connect the accumulator (battery) to the dc link of the motor drive system. Battery fed electric vehicles is required to function in three different modes namely: acceleration mode, normal and braking mode. During acceleration and normal modes, the power flow is from battery to motor whereas during braking or regenerative mode the kinetic energy of the motor is converted into electrical energy and fed back to battery. The DC-DC converter is required to perform mainly two functions: first to match the battery voltage to the motor rated voltage and second to control the power flow under steady-state and transient conditions, so that the drive performance is as per the requirement. The proposed controller is adaptive PI controller for bi-directional dc-dc converter feeding a dc motor and its energy recovery due to regenerative braking has been demonstrated. The simulation and performance analysis of battery-operated electric vehicle under different drive condition are also presented through MATLAB/Simulink.