Duty cycle-based start-up control for a ZVS bidirectional DC-DC converter

When operating in island mode, DC-based microgrid mainly starts up through batteries and bidirectional DC-DC converters. In conventional way, an extra start-up circuit is required to limit the surge current, which not only decreases the efficiency but also increases the cost. In this paper, the generation mechanism of the surge current is analyzed, through which the duty cycle control scheme is proposed. Without an auxiliary start-up circuit, the converter can safely start up with controllable peak current value by using this method. Detailed analysis and formula derivation of the scheme in different operation modes are presented and the simulation and experimental results are exhibited to verify the effectiveness of the scheme, which provides a simple, safe and economic way for black start-up.