DESIGN AND DEVELOPMENT OF DUAL ACTIVE BRIDGE BASED FAST CHARGING ARCHITECTURE FOR ELECTRIC VEHICLES

Abstract

In this thesis, a single phase on-board charger is proposed for fast charging of an electric vehicle (EV) with Vehicle to Grid capabilities. This novel fast charging architecture for electric vehicles comprise of the two key components: the Interleaved Boost Converter and the Dual Active Bridge converter. The Interleaved Boost Converter serves as the power factor correction unit and operates in a dual control loop configuration. The outer loop maintains the desired DC-link voltage, while the inner current loop ensures unity power factor operation by aligning the grid voltage and grid current. The inner current loop employs a Proportional-Resonant (PR) controller, which eliminates steady-state error more quickly and reduces current tracking error more effectively than a Proportional-Integral (PI) controller, which is used in the outer voltage loop for stable dynamic operation. The DAB DC-DC converter is the main component for power transfer between the output of the Interleaved Boost Converter and the EV battery. It is highly favored for its galvanic isolation, high power density, bidirectional power flow capability, and innate soft switching, all of which are crucial for maintaining efficient and fast charging. A high frequency transformer is used in the dual active bridge which ensure the high frequency switching operation, high gain and also reduces the size of filter used in the battery side. The DAB operates in a closed loop, ensuring constant voltage application even under variable load conditions. This closed loop control system, designed to integrate the DAB with the main grid via the PFC IBC, adheres to the IEEE standard (IEEE-519) for Total Harmonic Distortion (THD) of grid current, ensuring compliance with prescribed power quality standards. The mathematical and electrical models are developed for the proposed system and overall efficacy is verified through MATLAB/Simulink simulations, which assume a resistive load. These simulations demonstrate the system’s ability to efficiently manage power transfer, maintain high efficiency, and comply with power quality standards, thus proving the viability of the proposed fast charging solution for electric vehicles.