Hold-up time compensation method for phase-shifted full-bridge converter using dual-active-clamp-snubber

Abstract

In general, the power supply must regulate the output voltage for a time called the 'hold-up time' even when the AC input is lost. At this time, since the link capacitor voltage decreases as the energy stored in the link capacitor is used, the DC/DC converter must be designed to operate in a wide input range to ensure a hold-up time. This paper proposes a hold-up time compensation method for phase-shifted full-bridge (PSFB) converter using a dual-active-clamp-snubber. The proposed method allows the PSFB converter to operate at the maximum duty ratio in the nominal state, and the voltage gain between the nominal state and the hold-up state is continuous. Additionally, it can be designed with a high turns-ratio, low diode voltage rating, and a small output inductor. As a result, this reduces loss due to primary side current, diode conduction loss, and loss of the output inductor, leading to high efficiency. The validity of the proposed circuit was verified with a prototype converter designed with $300 \sim 400 V$ input and $56 V/715 W$ output.