A COMBINATORY AC AND DC CHARGING APPROACH FOR ELECTRIC VEHICLES

Abstract

The proposed work presents a combinatory AC and DC charging approach for electric vehicles aimed at reducing charging time and improving flexibility without relying on expensive off-board fast-charging infrastructure. Conventional onboard AC chargers are limited by low power ratings and long charging durations, while DC fast chargers require high investment and grid capacity. To address these challenges, the proposed system integrates both AC and DC charging capabilities within the vehicle by utilizing existing drivetrain components such as the inverter and motor windings. A dedicated DC input port is introduced through the motor neutral and inverter negative rail, enabling direct connection to external DC sources like solar panels, DC microgrids, and energy storage systems. The drivetrain inverter is operated as an interleaved DC-DC converter, allowing high-power DC charging, while the onboard Type-2 charger manages AC charging. The system supports three modes of operation: AC-only, DC-only, and simultaneous AC/DC charging, thereby enhancing charging speed and energy utilization. A coordinated control strategy ensures stable DC-link voltage, avoids circulating currents, and maintains unity power factor during AC operation. Simulation and experimental validation confirm the effectiveness of the proposed method, demonstrating improved charging performance, reduced dependency on infrastructure, and enhanced adaptability to hybrid energy environments.