Non‐isolated bidirectional DC–DC converters with multi‐converter functionality employing novel start‐up and mode transition techniques

This work targets reducing the mode transition time drastically, for two of the bidirectional DC–DC converters (BDCs) employed in energy storage systems, simultaneously proposing a smooth start‐up process. Two different mode transition techniques are introduced for topology A (proposed) and topology B, respectively, whose transition times are much smaller than the existing transition techniques. Topologies A and B are capable of performing all basic converter operations, i.e. buck, boost, inverting buck–boost and non‐inverting buck–boost in bidirectional mode, which allows the operating voltage ranges of both V 1 and V 2 to be increased perceivably. Both topologies are compared based on mode transition methodology, stress on the converter switches, inductor size and rating. A start‐up technique is also advocated for both topologies so that the start‐up response could be smooth. Two 400 W BDCs are designed with voltage levels of 60 and 120 V and experimentally verified for efficient start‐up, mode transition and steady‐state operations. Both mode‐transition techniques proposed here, take 2 μs for the current reversal on the battery side from +5 to −5 A.