Optimized Control of Dual-active-bridge DC/DC Converter Based Power Electronic Transformer With Dual-phase-shift Control

This paper focused on dual-active-bridge (DAB) DC/DC converter, which is a crucial part of power electronic transformer (PET). Through the analysis of DAB DC/DC converter with single-phase-shift (SPS) control and dual-phase-shift (DPS) control, the concise expressions of transmission power and backflow power are deduced, while the equivalent circuits are given. Aiming to obtain the optimal combination between D1 (inner phase shift ratio) and D2 (outer phase shift ratio), an optimal DPS control scheme is proposed for DPS control by employing an evaluation coefficient to investigate the influence of the disturbances of control variables on the transmission power and backflow power. It can minimize the backflow power and reduce the power losses. Simulation results are provided to validate the correctness of theoretical analysis and the effectiveness of the proposed scheme.