Bidirectional energy management in electric vehicle chargers through the nonlinear control of DC-DC converters

Abstract

Bidirectional chargers play a key role in linking electric vehicles to smart grid infrastructure, enabling seamless energy interaction, as they enable energy to be exchanged in both directions, i.e., allowing energy to flow from the grid to the vehicle (G2V) and vice versa (V2G). Nonetheless, overseeing bidirectional energy flow introduces considerable control complexities. This study presents a non-linear control approach adapted to the architecture of a bidirectional DC-DC converter, aimed at guaranteeing robust and optimized battery charging and discharging processes. During grid-to-vehicle (G2V) operation, the converter operates in buck mode, supplying the battery with either constant current (CC) or constant voltage (CV), depending on its terminal voltage. Conversely, in vehicle-to-grid (V2G) mode, the converter switches to boost mode, delivering power back to the grid at a regulated constant current. The proposed system and its control approach are validated through simulations conducted in Matlab/Simulink, demonstrating their effectiveness. A comparative analysis against a standard linear PI-based control scheme shows that the proposed sliding mode control (SMC) technique delivers enhanced performance, guaranteeing accurate and resilient regulation of energy transfer.