Two-dimensional online efficiency optimization technique for dual active bridge converters

This paper proposes an online efficiency optimization technique for Dual Active Bridge (DAB) Converters. Simultaneous output voltage regulation and efficiency optimization are achieved through an advanced modulation scheme by exploiting the degrees of freedom offered by the DAB topology and with no requirements of preliminary calibration or converter characterization. A digital closed-loop controller implements voltage regulation and a two-dimensional optimization algorithm which continuously tracks the converter optimal efficiency point. The optimization loop relies on the simplex algorithm, which can be implemented in a hardware-efficient manner and without involving gradient calculations. Experimental results on a digitally controlled 196 kHz, 12 V-to-5 V, 10 W DAB prototype are reported confirming the effectiveness of the technique.