Active-Clamped Flyback DC-DC Converter in Three-Phase Application

The active-clamped flyback (ACF) dc-dc converter is typically used in applications with universal single-phase mains input. In this paper, design notes, simulation and experimental results of an ACF, supplied from rectified three-phase mains, are presented. Additionally, notes on simulation and measurement of the transformer magnetizing inductance are provided too. This ACF is designed to provide 5.5 V at its output with voltage-conversion ratio in range from 83.6 to 116.4. It was planned to use it as an auxiliary stand-by power supply of a wireless inductive-charging system. A 13 W prototype was built and tested. Maximum achieved efficiencies at 460 V and 640 V dc voltage inputs, with 100 % load, were 72.6 % and 69.1 %, respectively. The known fact that converters with high voltage-conversion ratio might suffer from lower efficiencies is, unfortunately, confirmed with the ACF topology as well. However, resulting efficiency, that is comparable with classical Flyback dc-dc converter, reduced EMI, ZVS operation and good thermal behavior could justify usage of the ACF in three-phase applications that are not cost-sensitive.