A Single-Stage High-Frequency-Link Modular Three-Phase $LLC$ AC–DC Converter

A new single-stage high frequency-link three-phase
$LLC$
ac–dc converter is proposed in this article. The proposed converter is featured by a boost full-bridge topology-based phase module with power factor correction (PFC) for the three-phase utility frequency ac  to single-phase high-frequency ac  conversion without a smoothed dc link, which brings the simplicity, cost-effectiveness, excellent modularity, and high efficiency into the power supply. The soft switching commutation can achieve over the wide range of load power with the assist of magnetizing current of a high frequency transformer in the
$LLC$
topology. The load power and voltage can be regulated by pulse frequency modulation  and phase-shift pulsewidth-modulation  depending on the load conditions. The effectiveness of the proposed converter is investigated by simulation and experiment of a 2 kW–50 kHz preliminary prototype, thereby the single-stage frequency conversion, PFC and zero voltage soft-switching  are revealed from a practical point of view.