Extending Soft-Switching Operating Range of Three-Phase Dual-Active-Bridge Galvanically Isolated Bidirectional DC/DC Converter by Employing PWM Control Strategy

Abstract

A switching control strategy for extending the soft-switching range of a three-phase dual-active-bridge (DAB) galvanically isolated bidirectional dc/dc converter under the zero-voltage-switching (ZVS) operating mode is proposed. The converter topology consists of two three-phase active bridges linked by Y-Y connected three-phase high-frequency transformers. One drawback of the conventional phase-shift control strategy is that soft switching is only possible within a restricted converter operating region. A novel pulse-width-modulation strategy to extend the conventional soft-switching operating mode region and its analysis are presented in this paper. A 10-kW prototype has been built, and experimental results are presented in order to demonstrate the validity of the theoretical analysis and the practical feasibility of the proposed strategy.