Global Modulation Strategy and Analysis of DAB Converter Based on Efficiency optimization

Abstract

In this paper, an Efficiency Optimization Strategy (EOS) is proposed to address the issue of low efficiency in the Dual Active Bridge (DAB) DC-DC converter across certain power ranges under wide voltage conditions, with the aim of further enhancing the converter's efficiency over a broad operating range. First, in the low power range, a phase-shift control strategy is introduced, which enables wide-range Zero Voltage Switching (ZVS) and near-optimal inductor current RMS values. Through this strategy, ZVS is ensured for all switches under light load conditions, while under medium load conditions, ZVS is lost for only two switches. Subsequently, in the high power range, the optimization target is smoothly transitioned to the optimal RMS current value by utilizing the natural ZVS characteristics of the DAB converter. The operating range of the EOS is effectively extended, further reducing current stress and RMS current values, thereby achieving global efficiency optimization of the DAB converter. Finally, an experimental platform is constructed for verification, and the correctness and effectiveness of the theoretical analysis are confirmed by the experimental results.