Dual active bridge converter and its control

Isolated bidirectional DC–DC (IBDC) converters are needed in a wide range of applications including DC microgrids, electric vehicles, and energy storage devices. Among various IBDC topologies, the dual active bridge (DAB) converter is one of the most promising solutions owing to its simple and symmetric structure, the capability of zero-voltage switching (ZVS) for all switches, and the wide voltage conversion range. This chapter presents the working principle and performance characterization of the DAB converter as well as its modeling and control. Four typical modulation schemes are introduced. Based on the single-phase shift modulation, active and reactive power flows are derived. Trade-offs among ZVS operation range, component current stress, and output power rating are analyzed, providing guidance for optimizing the inductance. In terms of control, large- and small-signal circuits of the reduced-order model are developed. The small-signal model is further improved by capturing the impacts of power losses. Two typical closed loop control strategies, output voltage feedback and output voltage feedback plus output current feedforward, are introduced and designed for an example DAB converter. Both the modeling methods and control strategies are verified by piecewise linear electrical circuit simulation (PLECS). The presented performance characterizations, large- and small-signal models, and control strategies offer practical design insights for DAB converters.