Three/Single-Phase Compatibility Single-Stage EV Charger With Six-Switch Full-Bridge Configuration
Ba Phu, Million Gerado Geda, Huu-Phuc Kieu, Dinh Bao Hung Nguyen, Sunju Kim, Sewan Choi
Abstract
This article presents a single-stage electrolytic capacitor-less AC-DC converter designed for EV chargers, featuring a 6-switch full-bridge DC side configuration with both three-phase and single-phase compatibility. The proposed topology features three interleaved totem pole modules on the AC side and a 6-switch full bridge on the DC side, interconnected via a delta (Δ) transformer configuration. For three-phase grid operation, this article introduces an advanced duty cycle modulation technique to extend the ZVS range across a wide battery voltage range and enhance the THD performance of the grid current under varying load conditions. An unbalanced control method is proposed to mitigate low-frequency harmonic distortion in the charging current, effectively compensating for both sag and swell conditions in the grid voltage. The integrated buck-type power decoupling circuit is introduced for single-phase grid operation to absorb the second harmonic current component and eliminate the need for external components. To validate the proposed topology, an 11kW laboratory EV charger prototype was developed and tested, achieving a peak efficiency of 96.8% and a THD of grid current of 2.5%.