Current Stress Minimization of Dual-Active-Bridge DC-DC Converter Within the Whole Operating Range

Current stress minimization is one of the most important challenges for the steady-state studies of dual-active-bridge (DAB) dc-dc converter. Triple-phase-shift (TPS) control can minimize the current stress to the utmost extent, and a segmented analytical method-based TPS (SA-TPS) control has been proposed in this paper to minimize the current stress of DAB within the whole operating range. The full model of DAB with TPS control was classified into 12 operating modes by a complete operating mode classification method. On the basis of the analytical expressions of transmission power and current stress in different modes, the current stress minimization issue was transferred to inequality constraints' problems in different operating modes. The mathematical derivation process of the SA-TPS control method is described in detail, and the analytical expressions of current stress minimization results as a function of voltage conversion ratio and transmission power have been derived by solving the forward and reverse power transmission processes, respectively. The operating mode selection principle and the regularities of minimization results varying with transmission power and voltage conversion ratio have been explored. Experiments under different conditions have been implemented on a laboratory prototype to validate the correctness and effectiveness of the proposed SA-TPS control method.