Discrete Single-Phase-Shift Control Strategy with Transition Pulses of Dual-active-bridge DC-DC Converter

A discrete single-phase-shift (D-SPS) control with transition pulses is proposed to improve the dynamic response and eliminate the transient dc bias current for dual active bridge (DAB) dc-dc converter. By applying preset control pulses with discrete phase-shift duty ratios, the D-SPS control can achieve a fast dynamic response. However, unbalanced transmission powers are caused by the discrete phase-shift duty ratios in successive switching cycles, which lead to decreased efficiency and eventually saturation and faults of the transformer. Thus, transition pulses are introduced between each adjacent discrete control pulses to eliminate the dc bias current caused by the discrete phase-shift duty ratios. Theoretical analyses, parameter design, and control performance of D-SPS control with transition pulses for DAB dc- dc converter are given. Experimental results from a 96V-48V, 288 W, 50kHz DAB dc-dc converter are presented to validate the proposed D-SPS control method.