PROJECT TITLE :

Optimal Phase Shift Control to Minimize Reactive Power for a Dual Active Bridge DC-DC Converter

ABSTRACT:

Under non-unity voltage gain conditions, modulating the phase shift ratios in a dual active bridge (DAB) dc-dc converter can reduce reactive power and boost efficiency. Because a DAB can run in four different scenarios (forward/backward, buck/boost) and each scenario has five operating modes, determining the best phase-shift ratios to yield the smallest reactive power is difficult. DAB operational scenarios (forward/backward, buck/boost) can be transformed into one another so that only one scenario (forward/buck) is needed to be optimised. Next, this study uses a graphical way to show that each operational point of Modes 1, 2, and 5 can be mapped into that of Mode 3 with lower conduction losses, and only two modes need further investigation. These two approaches of optimization are developed step-by-step. Optimal phase-shift signals that reduce reactive power for four different DAB operating scenarios (forward/backward, buck/boost) have been described. The real implementation of global reactive-power minimization control is shown in a simple table and block diagram. The proposed control mechanism has been proven to be more efficient when compared to existing modulation schemes.