Research on Three-degree-of-freedom Control of Three-phase Dual Active Bridge to Minimize Current Stress

The three-phase dual active bridge converter has the advantages of high-power-density and easy realization of soft switching, which is very suitable for bidirectional high-power transmission applications. In this paper, a three-degree-of-freedom duty cycle control method is proposed to reduce the current stress under light load and voltage mismatch conditions. Firstly, there are different working modes with this control method are classified and compared through time-domain analysis. Secondly, taking the current stress as the optimization objective, the optimal operating trajectory in each mode is solved by Lagrange multiplier method, and the global minimum current stress operating method in full power range is obtained. Finally, a 30kW prototype is built to verify the effectiveness of proposed control method.