Wide Voltage Range Reconfigurable DAB Converter Realized by Monolithic Bidirectional GaN/Discrete SiC-FETs, and Planar Transformer

The standard dual active bridge (DAB) converter with symmetric full-bridge circuits on both the primary and secondary sides of a galvanic transformer has been widely recognized in automotive systems for its efficient performance within a limited voltage conversion range. However, when used in low-power applications or when a broader voltage conversion range (e.g., 200–800 V) is required, maintaining zero voltage switching (ZVS) becomes difficult, leading to a reduction in efficiency. This article presents the concept of a reconfigurable DAB (Re-DAB) converter to address this challenge. The proposed topology consists of a T-cell branch and a half-bridge cell in both the primary and secondary sides, which can be reconfigured as a full-bridge, half-bridge or hybrid circuit. By incorporation of SiC–FETs and a recently developed monolithic bidirectional GaN device in the proposed Re-DAB converter, different configurations are extracted aiming to preserve the ZVS operation with a high overall efficiency for a wide range of input/output voltage regulation. A planar transformer (PT) design using Pareto-Front optimization is also carried out for the galvanic isolation. Working principle of the proposed concept is discussed, while the design guidance of the PT, and the ZVS range analysis are given in details. A 6.6 kW/50 kHz prototype with a 98.2% peak efficiency for 200–800 V input voltage and 400 V output voltage is fabricated and its detailed experimental results in each of the operation modes are presented.