Self-Adapting Online Loss Minimization of a Dual Active Bridge in Buck and Boost Mode

In this paper, an online self-adapting and selfoptimizing algorithm for increased efficiency of a high power Dual Active Bridge (DAB) in Triple Phase Shift buck and boost operation is presented. The algorithm estimates internal losses and performs iterative optimization steps during operation in the direction of the steepest descent, without requiring additional high-precision voltage or current sensors. Due to the working principle of the algorithm it is ensured that only operation points with lower losses are chosen for the next optimization step. Experimental results demonstrate that switching angles derived from precalculated Circular Current Injection method or Triangular Current Mode modulation can be further improved to reduce losses. A loss reduction of approximately 20% can be achieved using a 450kW medium voltage DAB testbench.