Soft Start-Up Scheme of Dual Active Half-Bridge Converter for Mitigating Dead-time Effects

In this paper, a soft start-up scheme is proposed for dual active half-bridge converters where the impact of dead time is carefully considered. The voltage distortion occurs for the dead time durations where an additional power is induced by a circulating current flowing through the inductor. The transferred power charges the secondary half-bridge capacitors, leading to an inadequate increase in the output voltage during the start-up sequence. Based on the dead time effect analysis, it is possible to limit the maximum power by controlling the duty ratio during the start-up sequence. The proposed start-up scheme sequentially increases the duty ratio before changing the phase shift ratio. The duty ratio provides an additional degree of freedom in the DAHB converter, which can minimize the transferred power regardless of the dead time. The validity of the proposed method is verified by simulation and experiments results.