Impact analysis of a multi-variables modulation on the transformer of the dualactive-bridge converter

Abstract

This work proposes a novel analysis framework to model the dual-active-bridge (DAB) converter static behaviour when it is subjected to a multi-variables modulation. Novel equations that relate the transferred active power and the total transformer apparent power are derived and an iterative analysis process is proposed. The main objective is to define the total apparent power maps for a given active power level and find the lowest apparent power points. Based on that, the reduction of transformer volume and copper losses can be analysed. In general, it was observed that the lowest total apparent power is obtained for operation with D1 ξ D2 and tends to occur at small φ angles. Moreover, in these conditions, there is also the smallest transformer volume and the lowest copper losses. Experimental results at 800, 1200, and 1600 W of a DAB prototype are presented to validate the proposed analyses, where a maximum core volume variation of 35% was obtained for a given active power level.