A Decoupled Phase-Shift-Compensation ZVS Modulation Method for Three-Phase AC–DC DAB Converters With High-Frequency-Coupling Structure

The single-stage isolated power factor correction (PFC) AC-DC DAB converters have gained increasing attention for battery-charging applications, including electric vehicle (EV) chargers and battery energy storage systems (BESSs). Controlled through phase-shift modulation, their zero-voltage-switching (ZVS) performance is tightly coupled with other system parameters such as power, current stress, and total harmonic distortion (THD). This strong coupling complicates the modulation design when comprehensively targeting PFC, ZVS, low conduction current, and low THD. This paper proposes a common-mode phase-shift compensation (CMPSC)-based ZVS modulation method for a modified AC-DC DAB converter, in which the ZVS enhancement is decoupled from other system parameters, enabling a simpler approach to improve ZVS performance on the DC side. Two circuit implementations and two modulation strategies are presented. The proposed constant CMPSC (Const-CMPSC) and optimal CMPSC (Opt-CMPSC) methods are implemented on a prototype EV charger and compared with a baseline sinusoidal phase-shift (Sin-PS) method. Experimental results show that the peak efficiency is improved by 0.3% with the CMPSC method and by 0.6% with the Opt-CMPSC method. The light-load efficiency is further enhanced by more than 1.3% using Opt-CMPSC.