Modeling and Control of a 225-KW Grid-Interactive Bidirectional Fast DC Charger for Electric Vehicles

This paper presents the design and simulation-based evaluation of a 225 kW grid-interactive bidirectional fast DC charger for electric vehicles operating in both grid-to-vehicle (G2V) and vehicle-to-grid (V2G) modes. The proposed charger is developed in MATLAB/Simscape and integrates a two-level PWM AC/DC converter, a bidirectional DC/DC stage, an LCL-filtered grid interface, a regulated 1000 V DC-link, and a lithium-ion battery pack operating under CC and CC–CV control. The battery model and supervisory state-of-charge signal are reused from a previously validated electro-thermal and EKF-based battery framework and are embedded here within a charger-level architecture to study the coupled behavior of the battery, converter, and grid interface. Under nominal operation, the charger achieves near-unity power factor and low grid-current total harmonic distortion of 0.55% in G2V mode and 0.26% in V2G mode. The study also examines charger behavior under bidirectional mode transitions and disturbed-grid conditions including source-harmonic injection, voltage sag, frequency deviation, and reactive-power command tests. The results show stable bidirectional operation, preserved DC-link regulation, and acceptable current quality under both nominal and non-ideal conditions, providing a charger-level simulation reference for future real-time and experimental validation.