Design, Loss Analysis and MFA Modeling of DAB-based Fast Charger for Bidirectional Grid to EV Power Transfer

The Dual-Active Bridge (DAB) topology offers various advantages in the applications of Electric Vehicle (EV) charging and Vehicle-to-Grid (V2G) power transfer, such as high efficiency, soft switching, modular structure, and bidirectional nature. This paper presents the DAB design topology for fast EV charging and V2G energy exchange, considering minimum battery deterioration. The HV and LV switches are designed to operate at zero-voltage switching (ZVS). A systematic loss analysis of the designed DAB converter is carried out for performance evaluation at various load conditions. The converter is then modeled using the Multi-frequency averaging (MFA) technique. A small-signal model is computed, and the transfer functions are obtained independently for the current and voltage control design. Constant-Current Constant-Voltage (CCCV) algorithm is used for battery charging. The battery discharge to the grid is carried out using Constant-Current (CC) mode. Simulation is carried out using the MATLAB-Simulink tool to validate the developed system.